2001mars society convention part 4

Benefits of Modified Breathing Air for Spacecraft and Planetary Habitats

I. Kotliar; A. Prokopov[2001]

AbstractResidents of high altitude demonstrate normal physiological characteristics and show increased vitality and lesser morbidity.Subjects acclimatized to a low O2 (hypoxic) environment (corresponds to 14.5-11% O2 at the sea level) exhibited enhancedphysical endurance and increased resistance to stress-inducing and damaging factors and accelerated recovery in a variety ofconditions. Hypoxic stimulation reactivates the O2 saving genetic program, which is active in all mammal cells duringembryonic development, when O2 partial pressure in the uterus is comparable to that in the high mountains.

CO2 deficiency (hypocapnia) is a regular component of general stress reaction and is harmful for normal physiologicalfunctions. Positive effects of moderately increased CO2 (physiological hypercapnia) are well documented. CO2 hasdirect antioxidative action, suppressing production of superoxid-anion radicals in the mitochondria, and neutralizing thehighly-aggressive radical peroxynitrit.Application of normobaric moderately hypoxic-hypercapnic environment in manned space exploration has followingbiological benefits:

1. Adaptation to hypoxia result in significant enhancement of general stress-tolerance and improves general health,which increase operational reliability of crew.

2. Adaptation to hypoxia economizes oxidative metabolism, with significant reduction both of O2 and foodconsumption, but without productivity decline or health hazard. It can have a special value in emergency and inlong-termed interplanetary space missions, where amount of life-supporting resources is limited.

3. Inhalation of air with O2 concentration 8.5-10% is proven to induce radioprotective effect against X-rays and γ-rays.This effect finds application in cancer radiotherapy for protection of healthy tissues and can be used by astronautsfor short-time radioprotection in urgent situations.

4. Hypercapnic atmosphere in the greenhouse result in significant increase of plant productivity.

BackgroundIt is well recognized that the technical objectives of advanced life support system for long duration space and planetarymissions must include technologies that significantly reduce hazards, improve operational performance and operationalreliability of the crew, as well as promote self-sufficiency, and minimize the expenditure of resources. Technology mustbe developed to provide effective countermeasures to deconditioning effects of zero gravity.

Many of these objectives would be achieved by providing inside a space ship or planetary habitat a modified gaseousenvironment with moderately reduced oxygen and increased nitrogen and carbon dioxide, that combines both fire-preventive and health-promoting properties.

The strategy of maintaining of gaseous environment in human-occupied confinements, such as those found insubmarines, space ships and planetary habitats, is based mainly on the common sense presumption that the artificialbreathing mixture should simulate the Earth’s atmosphere as close as possible. It is commonly believed that anysignificant change in the proportion of constituent gases would be potentially hazardous for humans. Meanwhile, thealternative assumption is also possible. One can ask: what benefits a modified gaseous environment would provide forthe crew in prolonged space missions? A comparison is possible with the use of artificial Helium-Oxygen breathingmixture that is for a long time used in saturation diving. Without this mixture no professional diving deeper than 60-70m would be possible. The other example gives us the current practice of using normobaric hypoxic air for stimulatingadaptation to hypoxia. The numerous advantages of adaptation to hypoxia are broadly recognized today in the field ofsport and fitness training, and find growing application in the preventive and curative medicine.1,2,3

– 1 –

I. Kotliar & A. Prokopov; Hypoxico Inc. New York

OverviewNormobaric, moderately hypoxic air is similar to the altitude air of mountainous ski resorts. In the world more thanmillion people live in the altitude between 2500 and 4000 m., where oxygen partial pressure gradually decreases from14.7 kPa to 12.1 kPa, which corresponds from 15.4 to 12.7% O2 in the normobaric air. At this altitude humans andanimals easily develop tolerance or adaptation to hypoxia.4 The only difference between altitude (or hypobaric) air andnormobaric hypoxic air is that normobaric hypoxic air contains increased amount of nitrogen. This determines thespecific fire-preventive properties of breathable normobaric hypoxic air.

It is well documented that residents of high altitude demonstrate increased vitality and lesser morbidity from commondiseases.5,6 It is proven to be the result of adaptation to hypoxia.

At the beginning of hypoxia adaptation, mitochondrial respiration is decreased, thereby leading to a buildup of reducingequivalents that cannot be transferred to O2 molecules. This condition, called reductive stress, can paradoxically leadto enhanced formation of free oxygen radicals. Free radicals mediate expression of genes, responsible for molecularadaptation to hypoxia. Induction of hypoxia-inducible transcription factor (HIF-1alpha), activated at low pO2, explainthe multiple effects of hypoxia adaptation. HIF-1alpha mediates the expression of possibly hundreds of genes thatenable the cell to survive in a hostile environment.7

Mechanism of Hypoxia AdaptationMitochondria are able to change their morphological structure and enzyme spectrum in order to save oxygen underhypoxia influence. This result in more efficient oxygen utilization and, most important, in the reduction of basalemission of free oxygen radicals.8 Basal oxygen consumption in the body significantly decreases in adaptation tohypoxia. Remarkably, that basal oxygen consumption determines the rate of oxidative damage in DNA, which influencethe individual life span, as well as onset and development of age-related diseases.9 By reducing the basal mitochondrialemission of reactive oxygen species it is possible to inhibit oxidative DNA damage and diminish age-related decline ofDNA repair mechanisms.

In the human studies it was demonstrated that reduction of basal oxygen consumption results in diminishing of excretionof oxidative DNA repair product – oxo8dG.10 This is a direct evidence of efficacy of hypoxia adaptation in reductionof basal oxidative DNA damage in humans.

In the pathologic, uncontrolled conditions, such as extreme or prolonged oxygen deprivation, hypoxia “per se,” andespecially the hypoxia-reoxygenation episodes can cause destructive oxidative stress, followed by apoptosis or necrosisof involved cells. In the controlled, mild and intermittent hypoxia it would only induce enhancement of antioxidativecellular defense and adjustment of metabolic pathways.11,12,13

Intermittent normobaric hypoxia can be broadly defined as repeated episodes of inhalation of ambient air, having artificiallydecreased oxygen content, interspersed with episodes of inhalation of air with higher oxygen content. The primarydistinguishing feature of intermittent hypoxia is the presence of periods of recovery from oxygen deficit. They providesufficient time for anabolic responses while avoiding the detrimental effects of long-term severe oxygen deprivation.

Mechanisms of adaptation to hypoxia in the mammals have deep evolutionary roots. The fertilized egg cell begins itsdevelopment under very low ambient oxygen content. Partial pressure of oxygen in its microenvironment is near to thatat the top of Mount Everest. Increase of oxygen concentration would kill developing organism immediately, becauseits antioxidative defense needs time and proper stimulation to mature.

Impulse biorhythm of cyclic pO2 change was found in the uterus and intrauterine fetus of mammals. It is regarded asevolution-fixed, physiological mechanism aimed at increasing antioxidative defense of the fetus.14 Maintaining itscapacity during the individual life seems to be crucially important mechanism that is keeping the balance betweenpotentially destructive free radical oxydation and the reparative synthesys of damaged cellular structures.

– 2 –


Stimulating this mechanism by adaptation to intermittent normobaric hypoxia results in more significant increase ofnonspecific resistance to oxidative stress, than application of continuous, uninterrupted altitude hypoxic stimulus.3

Moderate hypoxia, especially if combined with exercise, facilitate adaptation and improvement of aerobic metabolism.Exercising in hypoxia result in increased hormonal response and enhanced release of Growth Hormone.15 In contrast,extreme and prolonged continuous hypoxia initiates catabolic processes, which result in reduction of muscle and bonemass. Similar effects are present in the microgravity conditions of space flights and in model experiments. Theseeffects are shown to be mediated by decreased production of GH, which accompanies detraining and disuse of muscles,ligaments and bones.16,7

The question is, what specific biomedical problems of manned space flights could be solved or ameliorated byimplementing a normobaric hypoxic gaseous environment?

Applications1. Hypogravity deconditioning

The impact of hypo-gravity deconditioning on the crew’s ability to conduct subsequent surface operations is asignificant concern. For example, the typical transit time for an Earth-to-Mars mission is 150 to 200 days. Becausethis extended time in zero gravity will contribute to bone and muscle loss in the crew members, these astronautscannot be expected to walk great distances easily when they reach Mars. Current space biomedical researchcontinues to study why bones loose more calcium during space flights, as well as changes in renal tissue, thedecrease in body fluids, insulin and glucose disturbances and the development of a secondary immunodeficiency.It was shown that many of these troubles are mediated by decreased basal production and pulsatile release of GrowthHormone in hypogravity.16 GH activity goes far beyond the effect of any other hormone. It not only modulatesbiological aging, but also significantly improves physical and mental performance and prevents muscular atrophyand osteoporosis. Researchers have proven GH therapy can reverse the biological effects of aging by many yearsand dramatically improve physical fitness and bone density.

The effective countermeasures against detrimental effects of hypogravity used in the long orbital flights on “Mir”station, were based on the intensive treadmill exercise. Unfortunately, this exhaustive training requires more thanthree hours each day to achieve preventive effect. The “Mir” cosmonauts preferred to use this countermeasure onlyfor two hours daily, which is still very expensive in resources and time-consuming.

Abundant studies confirmed that physical exercising in hypoxia result in exaggerated metabolic changes in thebody.1,3,15,17 An individualized protocol of hypoxic training provides a dramatic increase of GH production.

In a practical view, exercise in normobaric hypoxia would be useful for intensifying endogenous GH release inastronauts, as well as in subjects to whom heavy resistance training cannot be applied.

2. RadioprotectionIt is widely known that rapid, heavy doses of radiation, released by a solar flare can cause severe cellular damage.Most of a solar flare’s energy is in alpha and beta particles that can be stopped with a few centimeters of shielding.

It is well known that radiation damage in cells is augmented dramatically by increase of oxygen partial pressure (socalled “oxygen effect in the radiation injury”). It is established that the molecular-biological mechanism of radiationeffect on the living organisms is mediated by massive production of oxygen free radicals, released by radiolysis ofwater molecules.

By means of acute decrease of oxygen partial pressure in the body one can achieve the significant radioprotectiveeffect in cells.18

– 3 –


The inhalation of hypoxic air, containing 8-8.5% O2, instead of ambient air, reduces oxygen content in the tissuesmore than on 50%. It results in marked, though short-termed (about 30-min.) radioprotective effect against ß andY rays. In some emergency situations this complementary technique would provide sufficient time for astronautsto reach the stationary radiation shelter. Astronauts, adapted to hypoxia, would not suffer negative effect from thislow level of oxygen.

The astronauts will spend about six months traveling to Mars, eighteen months on the surface, and six months returningto Earth. The permanent habitats of the Mars base can be covered with thick layers of soil to provide full-time radiationprotection, so nearly all the crew’s radiation exposure would occur during the year of interplanetary travel.

The possibility of long-termed radioprotection against cosmic rays can be employed by use of the phenomenon ofhypoxic hypometabolism, which develops in mammals under prolonged hypoxia. Application of uninterrupted hypoxicstimulus down-regulates metabolism and decreases body temperature, especially during the night sleep. Hypoxichypometabolism can be used both for radioprotection of crew and saving resources during interplanetary flight.

Advantages of Increased Carbon DioxideThe potential advantages of increased carbon dioxide (hypercapnia) in the modified gaseous environment also merit discussion.

Physiological hypercapnia is associated with a number of positive biological and therapeutic effects, such as increase in thecerebral and myocardial blood flow, acceleration of oxyhemoglobin dissociation in the capillaries and enhancement of bloodperfusion in functionally active organs.19 There is abundant evidence of enhanced capillary growth, increased collateralblood vessels development under intermittent hypercapnia applications. Naturopathic medicine and balneotherapy sincelong time successfully explore different protocols of increased CO2 application to produce curative effects.

It is well proven that moderate hypercapnia provides protective effect in severe hypoxia. The direct protective actionof carbon dioxide against hypoxic injury during bypass operations was reported.20 Protection of blood coagulationhomeostasis in severe hypoxia by carbon dioxide was shown.21 CNS tolerance to hypoxia can be increased promptlyand sufficiently by purposeful elevation of inspired carbon dioxide partial pressure.22 Protective effect of increased CO2on calcium metabolism in immobilization osteoporosis was demonstrated.23

It was shown recently, that carbon dioxide provide direct antioxidative action, suppressing concentration –proportionally the production of superoxide-anion radicals in the mitochondria, and neutralizing the other highly-aggressive free radical peroxynitrit.24,25,26

Actually CO2 in proper concentration plays in the body the role of an abundant, easy available and fast actingantioxidant, which protects from depletion the other, slower functioning components of antioxidant network system ofthe body under condition of oxidative stress.27,28,29 The review of physiological effects of moderately elevated CO2levels presented in a joint NASA / ESA / DARA study.30

And last, but not least: the productivity of plants and algae in an artificial planetary ecosystem can be enhancedsignificantly by increased ambient CO2.

ConclusionsWe can summarize that numerous benefits of moderately hypoxic-hypercapnic gaseous environment in the spaceexploration human activity are highly promising. Remarkably that this approach would be synergistically favorable forspace flights managing: it eliminates completely the fire hazard; it results in enhancing of general health and operationalreliability of crew; it increases positive effects of exercise and reduces oxygen consumption.

The detailed questions concerning specific protocols of application of such modified atmosphere should be answeredduring future biomedical research in simulated space missions.

– 4 –


References1. Radzievskii P. Use of hypoxic training in sports medicine. Vestn Ross Akad Med Nauk 1997;(5):41-62. Berezovskii VA, Levashov MI. The build-up of human reserve potential by exposure to intermittent normobaric hypoxia Aviakosm Ekolog

Med 2000;34(2):39-433. Bailey DM, Davies B, Baker J. Training in hypoxia: modulation of metabolic and cardiovascular risk factors in men. Med Sci Sports Exerc

2000 Jun;32(6):1058-664. Hochachka, P.W.Gunga, H.C.Kirsch, K. Our ancestral physiological phenotype: an adaptation for hypoxia tolerance and for endurance

performance? Proc Natl Acad Sci U S A 1998 Feb 17;95(4):1915-205. Curran LS; Zhuang J; Droma T; Moore LG. Superior exercise performance in lifelong Tibetan residents of 4,400 m compared with Tibetan

residents of 3,658 m. Am J Phys Anthropol, 1998 Jan, 105:1, 21-316. Mortimer EA Jr, Monson RR, MacMahon B. Reduction in mortality from coronary heart disease in men residing at high altitude. N Engl J

Med 1977 Mar 17;296(11):581-57. Ted S. Gross, Nagako Akeno, Thomas L. Clemens, Svetlana Komarova, Sundar Srinivasan, David A. Weimer, and Sergey Mayorov,

Physiological and Genomic Consequences of Intermittent Hypoxia. Selected Contribution: Osteocytes upregulate HIF-1 in response to acutedisuse and oxygen deprivation. JAP.Vol. 90, Issue 6, 2514-2519, June 2001

8. Chavez JC, Pichiule P, Boero J, Arregui A. Reduced mitochondrial respiration in mouse cerebral cortex during chronic hypoxia. Neurosci Lett1995 Jul 7;193(3):169-72 AD

9. Beckman, K.B. and Ames, B.N. (1998). The free radical theory of aging matures. Physiological Reviews . Vol. 78 . No 2. April 1998. 547-581.10. S Loft, A Astrup, B Buemann, and HE Poulsen Oxidative DNA damage correlates with oxygen consumption in humans FASEB J. 1994. 8: 534-537.11. Zhuang J, Zhou Z. Protective effects of intermittent hypoxic adaptation on myocardium and its mechanisms. Biol Signals Recept. 1999 Jul-

Oct;8(4-5):316-2212. Sokolov E.I., Mushinskaya K.V., Davydov A.L., Starkova N.T., Ehrenburg I.V., Tkatchouk E.N. Effects of the interval hypoxic training on

lipid peroxidation in non-insulin dependent diabetes mellitus. Hyp. Med. J. 1999. V. 7. N 3-4. P. 37-40.13. Gulyaeva N.V., Tkatchouk E.N. Antioxidative effects of interval hypoxic training. Hyp. Med. J. 1997. V. 5. N 3. P. 18.14. Chizhov Aia. Physiologic bases of the method to increase nonspecific resistance of the organism by adaptation to intermittent normobaric

hypoxia. Fiziol Zh 1992 Sep-Oct;38(5):13-715. Kjaer M, Hanel B, Worm L, Perko G, Lewis SF, Sahlin K, Galbo H, Secher NH. Cardiovascular and neuroendocrine responses to exercise in

hypoxia during impaired neural feedback from muscle. Am J Physiol 1999 Jul;277(1 Pt 2):R76-8516. G. E. McCall, C. Goulet, R. R. Roy, R. E. Grindeland, G. I. Boorman, A. J. Bigbee, J. A. Hodgson, M. C. Greenisen, and V. R. Edgerton.

Spaceflight suppresses exercise-induced release of bioassayable growth hormone. JAP.Vol. 87, Issue 3, 1207-1212, September 199917. Schmidt W, Dore S, Hilgendorf A, Strauch S, Gareau R, Brisson GR. Effects of exercise during normoxia and hypoxia on the growth hormone-

insulin-like growth factor I axis. Eur J Appl Physiol Occup Physiol 1995;71(5):424-3018. Strnad V, Sauer R, Tacev T. Hypoxic radiotherapy. The radioprotective effect of acute hypoxia in the radiotherapy of tumors in the abdominal

area. Strahlenther Onkol 1994 Dec;170(12):700-319. Fried, R. (1993). The Psychology and Physiology of Breathing In Behavioral Medicine, Clinical Psychology, and Psychiatry. New York.

Plenum Press.20. Hanel F, von Knobelsdorff G, Werner C, Schulte am Esch J. Hypercapnia prevents jugular bulb desaturation during rewarming from

hypothermic cardiopulmonary bypass. Anesthesiology 1998 Jul;89(1):19-2321. Pak GD; Sverchkova VS. Role of carbon dioxide in the correction of coagulation homeostasis during hypoxia. Kosm Biol Aviakosm Med 1987

Nov-Dec;21(6):43-722. Lambertsen, C.J. CO2 – O2 interactions in extension of tolerance to acute hypoxia. Final report. University of Pennsylvania Medical Center.

Rep. No. 4-20-95 (Springfield, VA, 1995: NASA and National Technical Information Service, dist).23. Drummer C, Friedel V, Borger A, Stormer I, Wolter S, Zittermann A, Wolfram G, Heer M. Effects of elevated carbon dioxide environment on

calcium metabolism in humans. Aviat Space Environ Med. 1998; 69: 291-824. Beckman, J.S. and Koppenol, W.H. (1996) Nitric oxide, superoxide, and peroxinitrite - the good, the bad , and the ugly. Am. J. Physiol. 271.

Pp. 1424-1437.25. Pryor, W.A. et al.(1997) The catalytic role of carbon dioxide in the decomposition of peroxynitrit. Free Radical Biology and Medicine. Vol.23

No 2. Pp 331-338.26. Squadrito, G.L. and Pryor, W.A. Oxidative chemistry of nitric oxide: the roles of superoxide, peroxynitrite and carbon dioxide. Free Radical

Biology and Medicine. 1998. Vol.25 ,No 4-5. 392-40327. Zhang, H. et al. Inhibition of peroxynitrite - mediated oxydation of glutathione by carbondioxide. Arch. Biochem.Biophys. 1997. 339. 183-18928. Kogan, A.K. et al. Carbon dioxide and generation of reactive oxygen species by mitochondria. Dokl. Akad. Nauk.1995. Vol.340 No.1. 132-13429. Kogan, A.K. et al. Further evidence that CO2 inhibits the production of superoxide anion radicals in tissue phagocytes. Dokl. Biol. Scienses

1996. Vol. 348. 225-227.30. Frey MAB, Sulzman FM, Oser H, Ruyters G. The effects of moderately elevated carbon dioxide levels on human physiology and performance:

a joint NASA – ESA - DARA study – overview. Aviat Space Envir Med. 1998; 69: 282-4.31. Useful links: www.hypoxoco.com; www.hypomed.ch; www.hypoxia.ru; www.go2altitude.com

– 5 –


Non-Propulsive Access to the Martian Surface

Michael A. Pelizzari[2001]

AbstractWhen humans begin to systematically explore and settle Mars, the addition of rocket exhaust gases to the thin Martianatmosphere will irreversibly alter its composition, and its reactivity with exposed surfaces. Scientists on Mars will thenbe hampered by the challenge of distinguishing anthropogenic from pristine features of their objects of study, a fact thatwill erode the value of their contributions to comparative planetology. The problem can be avoided, or at leastmitigated, by conducting as much activity as possible using emission-free vehicles and power sources. Transportationbetween ground and space can be accomplished without rocket propellants, either by shooting payloads into space withguns (mass drivers), or by transferring momentum to them through ultra-long cables (space tethers). The GunTransportation System would consist of electromagnetic “coil guns” or conventional expanding-gas guns, either ofwhich must be hundreds of kilometers long to achieve escape velocity at human-survivable accelerations. The CableTransportation System would consist of skyhooks, space elevators, and other tether-based elements, hundreds orthousands of kilometers long. Both transportation systems would be easier to deploy at Mars than at Earth, due to itssmaller size, lower gravity, and thinner atmosphere.

IntroductionThe atmosphere of Mars is considerably thinner than Earth’s, and thus more vulnerable to alterations in its compositionby human activity. Future studies of the atmosphere, its chemical effects on surface features, and its interactions withMartian biota (if any), may be hampered by such alterations. This paper identifies a major risk of human activity onMars to the science of biology: the destruction of life forms unique to Mars before they are ever discovered. Restrictinggaseous emissions on the Martian surface, especially rocket exhausts, would mitigate this risk by preserving the pristineatmosphere to which the hypothesized life forms have adapted. To this end, non-propulsive alternatives to rockets areproposed for launching payloads into space from the Martian surface.

Momentum can be transferred to payloads either by shooting them from the surface with guns,1 or by lifting them withtethers that reach the ground from orbiting satellites.2 Payloads are assumed to include human beings. Thereforeaccelerations must not exceed human physical endurance limits, a restriction that translates into minimum lengths ofgun barrels and tethers on the order of 400 km to reach escape velocity. This is long for the gun but short for the tether.Building a 400-km gun on Mars would require a construction, earth-moving, tunnel-drilling megaproject to produce astraight or near-straight support structure of that length. Three sites whose favorable terrain-slopes would minimize theamount of work are examined.

Tethers as short as 400 km must rotate end over end as they orbit Mars, in order for their rotation and orbital speeds tonearly cancel where they pick up payloads.3 Such rotating tethers, which touch down many times per orbit, are calledasynchronous skyhooks to distinguish them from synchronous skyhooks, or “space elevators.” The latter are muchlonger and corotate with Mars. The space elevator is essentially a building so tall that the centrifugal force of Mars’rotation would keep it from falling down.4 Skyhooks are usually perceived as operating only in the equatorial plane,serving only equatorial launch sites. Because Mars explorers and settlers would probably rule out options demandinglong journeys to reach their launch facilities, we consider skyhooks capable reaching non-equatorial latitudes.

Search for Primordial LifeOf central interest to exobiologists is the search for pre-bacteria, the hypothesized missing links between nonlivingchemical systems and the simplest known independent life forms, the bacteria. Terrestrial searches for them haveyielded nothing, either in the modern biosphere or in the fossil record. The transition from known non-living organicmolecules to the first bacterium is a gigantic leap in chemical complexity, inexplicable by evolutionary theory without

– 1 –

Michael A. Pelizzari; Virtual Galactonautics, [email protected]

intermediate forms. The lack of living bacterial precursors lends credence to panspermia, the hypothesis that bacteriafell to Earth from an extraterrestrial source, and the prediction that their ancestors can be found on their planet of origin.Following the recent discovery of bacteria-fossil-like structures in a Martian rock recovered from the Antarctic ice sheetas a meteorite,5 some exobiologists regard as inevitable the transfer of bacteria between planets, aboard rocks dislodgedfrom their parent bodies by asteroid or comet impacts. After the Earth, Mars is the second most likely birthplace ofbacteria in the solar system, and therefore the next place to search for pre-bacteria. If pre-bacteria exist on Mars in aform that would be recognizable to science, they must be more fragile than bacteria and unable to survive in space.Otherwise they too would have survived the interplanetary journey aboard the impact ejecta that brought Martianbacteria to Earth. By this hypothesis, seekers of pre-bacteria should go to the Martian surface.

It is equally possible that bacteria evolved on Earth from ancestors so fragile that they left no fossils, and have sincebeen wiped out by one or more global changes, such as oxygenization of the atmosphere. It has been argued that bacteriaappeared much too early in Earth history to have evolved here.6 The fact that bacteria have existed almost as soon asthe environment became hospitable to them might mean that they evolved very quickly from fragile precursors.Chemical reactions can proceed rapidly when triggered by some high-energy event, producing mixtures far fromthermodynamic equilibrium and rich in complex but unstable molecules, few of which persist as the energy dissipates.Some of these molecules might have become self-replicating on a time scale shorter than their mean lifetimes, andcapable of evolving within their dynamic chemical environment from one generation to the next. It would only take asingle bacterium to evolve in this primordial soup before it cools, for life to survive the aftermath of the triggering eventand gain a toehold on the planet. The fact that nothing much more complicated evolved for almost two billion years7

testifies to the robustness and stability of the bacterium, the most successful of life forms. By this hypothesis, bacteriacould have evolved either on Earth or Mars, and spread via impact ejecta to the other planet. If on Earth, pre-bacteriamay never be found. If on Mars, pre-bacteria may be found under the following conditions:

(1) persistent pre-bacterial life forms exist,(2) global change has not wiped them out,(3) they are recognizable as life, and(4) they survive human intrusion into their environment.

Condition (4) may require the imposition of constraints on human activity within or near the hypothesized biosphere ofMars, especially activities such as rocket launches that pollute the atmosphere. If any rocket-plume constituent is lethalto pre-bacteria, it could be spread planet-wide by the winds of Mars, exterminating pre-bacteria before they arediscovered by science.

Yet a third possibility is that bacteria evolved around some star other than the sun, and fell to Earth and/or Mars onmeteors captured by the sun during a close passage of the star.6 This would be the only viable hypothesis if it tookbillions of years for bacteria to evolve, in which case the search for pre-bacteria would be just as fruitless on Mars ason Earth. But the current prevailing view of evolution, known as punctuated equilibrium, is that life evolves in burstsseparated by long stretches of stability.8 The first such burst might have been the giant leap from nonliving precursorsto the first bacteria 3.5-4.0 billion years ago, perhaps triggered by an asteroid falling into the primordial soup in the finaldays of planetary accretion. Modern biologists need not invoke billions of years of evolution around some ancient starto accept the early appearance of bacteria on Earth or Mars.

Rocket Contamination FootprintsThe Mars Society’s proposal for human exploration, known as Mars Direct, calls for launching a new crew to theMartian surface at every launch window and returning that crew to Earth through the next launch window.9 Thesewindows are separated by one Earth-Mars synodic year, or 780 Earth days. The outbound rocket would inject little ifany exhaust gas into the atmosphere of Mars, because deceleration would be accomplished by aerobraking. But theEarth Return Vehicle (ERV), a methane-oxygen burner, would inject almost its entire propellant load of 96,000 kg intothe Martian atmosphere as water vapor and carbon dioxide. The effect of this injection on the Martian atmosphere can

– 2 –


be grasped by noting the masses of water and carbon dioxide occurring there naturally. Table 1 gives the atmosphericcompositions of Earth and Mars, along with other data needed to estimate the column densities of water and carbondioxide above their surfaces. Figure 1 gives the corresponding relative humidity. From these it is clear that water vaporis a trace constituent in the Martian atmosphere, unlike carbon dioxide. The reverse is true in Earth’s atmosphere,though both gases are trace constituents in the driest regions. Therefore in assessments of the environmental impact ofhydrocarbon burning, water vapor must be regarded as the pollutant on Mars, and carbon dioxide the pollutant on Earth.

One can quantify the environmental impact of rocket exhaust by expressing the mass of each exhaust gas in terms ofthe natural abundance of that gas in the atmosphere. For this purpose, let us define the footprint of a gas source to bethe surface area on a planet above which the mass of an atmospheric constituent would be doubled by emission fromthe source. Thus the water footprint of an ERV launch on Mars would be the surface area on Mars above which thenatural atmosphere contains 43,200 kg of water, which is the mass of water expelled by the ERV. Numerically, thefootprint is simply the mass of the constituent gas in the rocket exhaust divided by the column mass of that gas in theundisturbed atmosphere.

Table 1. Atmospheres of Earth and Mars.10,11 Column air masses are shown for the constituent gaseswhose densities would be increased by hydrocarbon-burning rockets.

igure 1. Relative humidity on Mars compared to the range of relative humidity occurring on Earth.Curves were derived from the total pressures and H2O abundances in Table 1,

using the saturation pressure of water vapor over condensed water shown at left.12

– 3 –


Table 2. Footprints of ERV launches (43,200 kg H2O, 52,800 kg CO2).

The water and carbon dioxide footprints of an ERV launch are shown in Table 2 for both planetary atmospheres. Thewater footprint on Mars is by far the largest number in the table, due in part to the extreme dryness of the Martianatmosphere. To illustrate how much drier Mars is than Earth, the volumetric water abundances in Table 1 wereconverted to curves of relative humidity vs. temperature. The results, shown in Figure 1, suggest that it never rains onthe Red Planet, and snows or frosts only on extremely cold nights or at high latitudes. Any cloud condensing from watervapor in the ERV rocket plume would quickly evaporate as the plume diffuses into the dry Martian air. The averagerelative humidity within the plume will exceed twice that of the pre-launch air until the plume has diffused to a cylinder2.06 km2 in cross section around the rocket path. At that point the carbon dioxide in the plume, by contrast, will havedropped to within 0.016% of its density in the undisturbed atmosphere.

Precautionary PrincipleAtmospheric oxygen, vital to most life forms on Earth today, is known to have caused a mass extinction of anaerobicbacteria some two billion years ago. Might water vapor do the same to Martian pre-bacteria? A handful of ERVs posesno risk, but as the exploration of Mars leads to settlements and commerce with Earth, rocket launches could become asignificant source of water vapor in the Martian atmosphere. The result could be a dramatic global increase in relativehumidity. How this change would affect the hypothesized pre-bacteria will remain a completely open question untilsomebody either discovers pre-bacteria or develops a scientific theory of pre-bacteria with some predictive power.

Given our state of ignorance of the roots of the tree of life, the precautionary principle should be given great weight aswe venture beyond the home planet. Although this principle has been stated in various ways, it always expresses theneed to err on the side of caution when science cannot provide the knowledge needed to perform traditional riskassessment and management. A recent summary of the precautionary principle reads as follows:13

When an activity raises threats of harm to human health or the environment, precautionary measures should be takeneven if some cause and effect relation-ships are not fully established scientifically.

Generalized from humans to entire biospheres, this principle has already motivated NASA’s efforts to protect otherplanets from terrestrial microbes by sterilizing interplanetary spacecraft. It should now motivate efforts to preserve thenatural composition of Mars’ atmosphere by developing alternatives to rockets.

Mass DriversMany mass drivers have been proposed over the years for launching payloads from planetary surfaces. All are basicallylinear accelerators, applying a force to the payload as it moves along an upward-inclined linear guide, or rail (barrel forgas guns). Whatever the nature of the force, electromagnetic, gas pressure, or psychic, we assume it is uniform alongthe rail and vanishes thereafter. To launch ERVs, the mass driver must produce muzzle velocities of at least Mars escape(5.03 km/sec), with acceleration low enough to avoid injuring the passengers, and with enough velocity margin tocompensate for aerodynamic drag along the post-muzzle flight path through the atmosphere. The payload may includeonboard rockets to reach higher speeds than the mass driver can deliver, but these would be fired far beyond the Martianatmosphere. The acceleration limit must account for the reduced tolerance of individuals whose physiologies haveadapted to Mars gravity (0.38 gees). Here we assume a 3-gee limit, which achieves Mars escape velocity after 430 km,if applied continuously along the rail. This length can be reduced to 390 km for launchers near the equator and pointingeastward, since payloads start with Mars’ rotation velocity at the loading end of the rail.

– 4 –


Based on the preceding considerations, we identify the following criteria for mass-driver sites, listed in decreasing orderof importance:

1. Terrain elevation increases uniformly over a very long distance (minimizes acceleration).2. Terrain elevation is as high as possible at the muzzle end (minimizes air drag).3. Terrain is near equator and slopes up toward the east (maximizes boost from Mars’ rotation).

With these criteria in mind, cursory inspection of a topographic map of Mars14 uncovered the potential mass-driver siteslisted in Table 3. The listed length at each site represents the longest uninterrupted stretch of uniformly sloping terrain,and therefore the longest straight section of rail possible at that site. Calculations of atmospheric drag loss at eachcandidate site are shown in Table 4. They are based on an assumed ERV mass of 20,000 kg, which is about the massof the Mars Direct ERV minus propellant and items to be left on the Martian surface.9

The last row in Table 4 shows how aerodynamically streamlined the ERV must be to keep drag losses below 100 m/sec.Clearly the Olympus Mons site outshines the others in this respect, because it would require little if any streamlining togive the ERV an effective cross section of 4.39 m22. Unfortunately, Table 3 shows that it is the worst of the three siteswhen rated by rail length, subjecting passengers to accelerations almost double the safety limit. One way around thisproblem would be to guide the ERV along a curved section of rail before feeding it to the straight section on the slopeof Olympus Mons. Figure 2 illustrates this idea with a 3-stage idealized model, in which the terrain slope jumps abruptlyfrom 0° to 5.44° at the base of the Olympus Mons cinder cone. Over the base, a curved section of launch rail with lengthS and uniform radius of curvature RC (Stage 2) is installed to connect a horizontal section (Stage 1) to the main inclinedsection (Stage 3). RC is driven by the need to keep centrifugal forces within passenger comfort and safety limits. Thisin turn determines the length of the curved section between its points of tangency with horizontal and sloped terrains (S~ 0.0949RC is the flat Mars approximation in this case). The more sharply Stage 2 curves, the less supporting structuremust be built to hold it up over the terrain, but the more jarring will be the ride for passengers due to centrifugal force.Figure 3 shows the acceleration required along Stage 3 and the speed of arrival from Stage 2, for several assumedcentrifugal-force limits. Also shown is the height of the rail above the base of Olympus Mons, which is where the gapbetween rail and terrain is greatest. Choosing a design involves a tradeoff between reducing the cost of the rail andincreasing the margin of safety for passengers, an exercise beyond the scope of this report. One plausible compromise,shown by arrows in Figures 2 and 3, is obtained using an upper limit of 1 gee on centrifugal force in Stage 2 (solid curvesin graphs). It has a 16.7-km curved section with a 185.3-km radius of curvature, allowing the ERV to enter Stage 3 at1.348 km/sec, a speed that can be boosted to escape velocity without exceeding the 3-gee linear acceleration limit. Thiscurved section crosses over the base of Olympus Mons at a height of 188 meters.

Table 3. Candidate sites for gun-type ERV launcher. Assumes uniform accelerationto escape velocity (5.03 km/sec) along a straight launch rail pointing eastward.

– 5 –


Table 4. Atmospheric drag losses of payloads fired from candidate ERV launch sites.The last three rows are based on an ERV mass of 20 metric tons.

Figure 2. Olympus Mons ERV launch rail with curve (length S, radius of curvature RC) to extendacceleration path. Vertical scale is exaggerated for clarity. Example (arrows) is described in text.

Our attention has focused on the Olympus Mons site because its superlative elevation places it above so much of theatmosphere that aerodynamic drag can be ignored. The two other candidate sites, Tharsis Montes and Hellas Planitia,would be more suitable for launching highly streamlined ERVs. If power is abundant at these sites, imparting extravelocity to payloads to compensate for drag would permit the launching of less streamlined shapes. With a 500-kmstretch of uniformly sloping terrain to accommodate it, a straight-rail mass driver could produce muzzle velocities of5.4 km/sec without exceeding the 3-gee safety limit.

SkyhooksThe Skyhook is a satellite whose function is to transport payloads to and from a terminal on the surface of a planet aroundwhich it orbits, using a space tether. Figure 4 illustrates both synchronous and non-synchronous types operating in theequatorial plane. For a payload to be picked up (or dropped off) easily as the satellite passes overhead, the tether tipmust come to a complete halt after its descent to the terminal, before proceeding on its way with (or without) thepayload. Kinematically, the ground and tether tip velocities must match at the moment of touchdown. For a circularorbit, the tether would behave like the spoke of a giant wheel rolling around the planet. The synchronous skyhook canbe regarded as a special case in which touchdown is a permanent condition, i.e., the giant wheel is stopped dead with

– 6 –


its spoke standing on the terminal. This is the immensely long space elevator, exemplified in science fiction by ArthurC. Clarke’s “orbital tower.”15 The shorter non-synchronous skyhook, or pinwheel, is much closer to physicalrealization.16 Of the two types, only the pinwheel could conceivably be developed in the near future to reach non-equatorial sites. For the space elevator to do so would require anchoring it to the ground, which would balance thecomponent of gravity normal to the equatorial plane and prevent it from wobbling between hemispheres. The enormityof such an anchor places it in the unforeseeable future of global engineering megaprojects, where space elevators willfigure prominently, as shown in Figure 5.

Figure 3. Parametrics of Olympus Mons launch rail with curved section of length S.Dotted line in (A) shows the safety limit for Stage 3 linear acceleration.Centrifugal acceleration in Stage 2 is also limited for passenger safety.

Solid curves in (A) and (B) represent the nominal 1 gee limit.Curves for 2 gees (short dashes) and 3 gees (long dashes) assume riskier limits.

Figure 4. Skyhook concepts. The synchronous skyhook (left), first described by Tsiolkovski,17

corotates with its planet. The non-synchronous skyhook (right), first described by Artsutanov,18

must spin to cancel its orbital velocity at touchdown.

– 7 –


Far Future: Space elevator: a special case of 1-armed pinwheel such that ωs = ωo = ωp (=14.62º/hrfor Mars).

Far Far Future: Constellation of space elevators,escalators, cross-threads: literally a World WideWeb. Dashed line is synchronous orbit.

Figure 5. Skyhooks of the unforeseeable future. Large blobs past stationary orbitare counterweights whose centrifugal force holds up the space elevators.

In designing pinwheels to launch ERVs from Mars, we follow the mathematical notation of Moravec3 but extend hisanalysis to nonzero latitudes. For a touchdown point at latitude λ, the velocity-matching condition is expressed in termsof the planet’s radius rp, orbital radius ro and angular velocities of the skyhook spin ωs, its orbital motion ωo and theplanet’s rotation ωp:

This equation contains the implicit assumption that the satellite is moving due east at touchdown if the planet is rotating.This is true for all touchdowns from an equatorial satellite, but from a non-equatorial satellite with orbital inclination i,it is only true at the latitude extremes of the satellite ground track, where λ = ± i. If the tether tip were to touch downat intermediate latitudes, the ground velocity component transverse to the orbital plane would not be canceled, and thetether would be subjected to extremely high aerodynamic drag through the corotating atmosphere. Therefore to reachhigh latitudes, the skyhook must be long enough to touch down only once or twice per orbit. Figure 6 illustrates thepermissible types of pinwheels, and defines the parameters needed to compute their lengths as functions of touchdownlatitude.

Pinwheel lengths are determined by synchronizing touchdowns with overflight of ground stations. This involves thefollowing steps:

• Relate angles swept by orbiter and ground station:

• Relate angles swept by orbiter and pinwheel arm:

Access to ground terminals at nonzero latitude λ:• Requires orbital inclination i = λ• Limits touchdowns to 2 per orbit, at latitudes ±λ where tether tip can descend vertically.

Number of pinwheel arms N:• N = any number if λ = 0.• N = 1 (asymmetric pinwheel) or 2 (symmetric pinwheel) if λ ? 0.

– 8 –


(ro − rp) ωs = ro ωo − rp ωp cosλ (1)

ωo TPASS = ωp TPASS + 2 π J (2)

ωs TTD = ωo TTD + (2 π / N) K (3)

Definitions:TTD = time between successive touchdowns at ground terminal.TPASS = time between successive overflights of ground terminal meridian.J = number of complete orbital revolutions per day.K = number of complete pinwheel revolutions per orbital period.Spin constraint on non-equatorial (λ <> 0) pinwheel:

• If pinwheel has one arm, K = 1 or K = 2 is allowed.• If pinwheel has two arms, only K = 1 is allowed.

Figure 6. Skyhooks of the foreseeable future.Tether tip descends to ground terminal, where arriving /

departing payloads are removed / attached. Tether tiprises again into space. Motion appears vertical to the

ground terminal crew at the moment of touchdown.

• Express angular velocities in terms of radii and the gravitational constant of Mars:

where rp = 3390. km

where G MP = 42828. km3/sec2

• Compute the integer number of orbits per day and spins per orbit:

• Obtain orbital radius vs. touchdown latitude for N-armed pinwheel by solving:

By solving Equations (2) and (3) for TTD and TPASS, we can write Equation (8) as

Solutions for 1- and 2-arm pinwheels were found by substituting Equations (4) through (7) into Equation (9), andnumerically searching for zeroes of the left-hand side. Results are plotted in Figure 7. Note that only the “1-arm, 2-orbits/day” curve represents true pinwheels. The other two curves are at synchronous orbit and therefore represent spaceescalators. These pinwheels have arms so long – more than two Mars radii – that acceleration poses no risk to passengers.

Much shorter pinwheels will work at the equator. If too short, their faster spin poses a risk to passengers. Accelerationat liftoff is simply the sum of the accelerations due to the tether’s orbital motion and its spin:3

This is plotted in Figure 8 for various pinwheel lengths, where it can be seen that the 3-gee safety limit is exceeded byany pinwheel whose arms are shorter than 307 km. The disadvantage of serving only the equator might be offset by thehigher frequency of overflights per day (up to 11) and the larger number of ground terminals served (up to 22 equatorialsites spaced 970 km apart). With these advantages and their more manageable lengths, equatorial pinwheels are likelyto emerge as alternatives to rockets much sooner than the high-latitude pinwheels described earlier. This is fortuitous

– 9 –


ωs = (ro ωo − rp ωp cosλ) / (ro − rp) (4)

ωo = (G MP / ro3)½ (5)

J = int(ωo/ωp) (6)

K = int(ωs/ωo) (7)

TTD − TPASS = 0 (8)

(ωo − ωp) K / N − (ωs − ωo) J = 0 (9)

(Liftoff acceleration) = (Surface gravity) rp3 / ( ro3 − ro2 rp) (10)

because it is near the equator where the first immigrants would be inclined to settle, given the Red Planet’scomparatively frigid climate. By the time Mars becomes so crowded that newcomers seek elbow-room at higherlatitudes, space tether technology may have advanced enough to build non-equatorial pinwheels to serve them.

Figure 7. Orbital radii of non-equatorial pinwheels. Ground terminal latitudes north and southmust equal the pinwheel’s orbital inclination, so one pinwheel can serve at most two latitudes.

Figure 8. Acceleration of pinwheel payloads upon liftoff from the Martian equator.Dotted line marks acceleration safety limit.

ConclusionsThe precautionary principle, originally formulated out of concern for human health and safety, instructs us to err on theside of caution when facing uncertainties with far-reaching consequences. By generalizing it to the health and safety ofplanetary biospheres, exobiologists stand a better chance of discovering their quarry. To the extent that the search forextraterrestrial life motivates the exploration and settlement of Mars, it is incumbent upon mission planners to heed theprecautionary principle. The Mars Direct Plan’s Earth Return Vehicle would inject environmentally significant amountsof water vapor into the Martian atmosphere. This would risk contaminating the surface locally, by hydration and otherreactions with rocks and soil below the rocket plume. Pre-bacteria, if they exist on Mars, could be extremely fragile and

– 10 –


altered or destroyed by the increase in relative humidity in their ecological niches. Larger scale Mars-Direct follow-onmissions also using rocket propulsion for Earth-return could, over time, globally increase the relative humidity on Mars,and risk eradicating pre-bacteria before they are ever discovered.

These risks can be mitigated by developing non-propulsive methods of departing the Red Planet, and utilize them onMar-Direct follow-on missions of exploration and settlement. Over the short term (decades), equatorial pinwheels couldreplace rockets. Imposing a 3-gee safety limit on acceleration would mandate pinwheel arm lengths of at least 300 km.Launching payloads without rockets from off-equatorial sites is more challenging, but several options could emerge overthe long term (50 years). Pinwheels with arms 6800-9500 km long could serve launch terminals within 53º of theequator. Mass drivers could launch payloads to Mars escape velocity from any latitude, provided the local terrainpermits a straight launch rail to be angled upward. The 3-gee safety limit would be exceeded by any rail shorter than400 km, a constraint that leaves only a handful of sites qualified for passenger-rated launchers. Olympus Mons is themost promising such site. And finally, space elevators and escalators could join this list of non-propulsive alternativesto rockets over the very long term (centuries).

None of these rocket alternatives has received much support beyond conceptual design work. It is hoped that the precautionaryprinciple, applied to hypothesized Martian life, will shine a spotlight on them and invigorate their development.

References1. “Midterm to far term applications of electromagnetic guns and associated power technology,” Miles R. Palmer, IEEE Transactions on

Magnetics, Vol. 29, 1993, pp. 345-350.2. Dynamics of Space Tether Systems, Vladimir V. Beletsky and Evgenii M. Levin, Advances in the Astronautical Sciences, Vol. 83, American

Astronautical Society, 1993.3. “A Non-Synchronous Orbital Skyhook,” Hans Moravec, The Journal of the Astronautical Sciences, Vol. 25, No. 4, pp. 307-322, Oct.-Dec. 1977.4. “The Space Elevator: ‘Thought Experiment’, or Key to the Universe?” Arthur C. Clarke, in Advances in Earth Oriented Applied Space

Technologies, Vol. 1, pp. 39-48, Pergamon Press, 1981. Accessible online (files http://www.islandone.org/LEOBiblio/ CLARK1.HTM,CLARK2.HTM, and CLARK3.HTM).

5. Imre Friedmann, “Fossil traces of life in the Martian meteorite ALH84001,” Fourth International Convention of the Mars Society, StanfordUniversity, August 24, 2001.

6. Robert M. Zubrin, “Interstellar panspermia and life on Mars,” Fourth International Convention of the Mars Society, Stanford University,August 23, 2001.

7. Andre Brack editor, The Origins of Life on Earth: Assembling the Pieces of the Puzzle, Cambridge University Press, 1998.8. S. J. Gould and N. Eldredge, “Punctuated equilibria: the tempo and mode of evolution reconsidered,” Paleobiology, Vol. 3, 1977, pp. 115-151.9. Robert Zubrin, “The Mars Direct Plan,” Scientific American, Vol. 282, March 2000, pp.52-55.

10. “Mars Atmosphere,” Mikhael Marov, in The Astronomy and Astrophysics Encyclopedia, Steven P. Maran editor, Van Nostrand Reinhold, 1992.11. C. W. Allen, Astrophysical Quantities, Third Edition, Athlone Press, 1973.12. Handbook of Chemistry and Physics, 53rd Edition, Robert C. Weast editor, Chemical Rubber Company, 1972, pp. D-147, D-148.13. “The New Uncertainty Principle,” David Appell, Scientific American, Vol. 284, January 2001, p. 18.14. Atlas of Mars, 1:25,000,000 Topographic Series, M 25M 3 RMC, 1976, I-961, U. S. Geological Survey.15. The Fountains of Paradise, Arthur C. Clarke, Harcourt Brace Jovanovich, 1979.16. “Advanced Space Propulsion Study – Antiproton and Beamed Power Propulsion,” Robert L. Forward, AFAL TR-87-070, October 1987.

Accessible online (search for “rotavators” in file http://www.transorbital.net/Library/D001_S03.html).17. Konstantin Tsiolkovski, 1895. See introduction in Ref. 4, online file CLARK1.HTM.18. Yuri Artsutanov, 1969. See acknowledgements in Ref. 4, online file CLARK3.HTM.

– 11 –


Pillars on Mars – Linking the Destinies of Ancient Greece and Future Mars

Jonathon Smith[2000]

IntroductionAs civilizations have risen and fallen, so have many human customs and traditions. However, it seems as if the humantendency to expand, whether it be to push further the borders of an empire or to push further the borders of knowledge,has always been present, from the very first human civilization on up.

The ancient Egyptians of the Old Empire managed to forge the first great human empire, which endured for almost 3,000years. They rose from a small, nomadic desert people, whose main daily activity was to secure water and food for thenext day, to become the creators of the great pyramids. Exactly how they were able to build these pyramids is still amystery to modern history and science. Even today, with our modern construction technology and advancedmathematics and science, such a feat would be monumental, and so it is a testimony to the ancient Egyptians’ drive andtenacity that they were able to build these huge funeral monuments with nothing but man and animal power.

The Greeks, whose civilization and culture dominated the Mediterranean world for nearly 400 years, were lessconcerned with the construction of monuments and more concerned with the building of human knowledge. You cannotfind one area of modern philosophy, science or politics that did not have its origin with, or was not affected by, theGreeks. They tirelessly and persistently asked the question “why” and tirelessly and persistently sought an answer, andit seems with great success. Some modern scholars claim the Greeks single-handedly advanced civilization over athousand years.

The Romans, who succeeded the role of the Greeks as the dominant force in the Mediterranean, took many of the Greekconcepts to heart. However, the Romans were altogether a more practical people, and their advancements tended to beon a more practical, usable scale. They were among the first people to have a city with over a million inhabitants, andsome of the systems they developed to support such a metropolis are still used today. The Romans built huge aqueductsto allow a constant influx of fresh water to the people of Rome. Irrigation projects had been done before, but nothinglike the aqueducts had even been conceived of until the Romans. Also, the Roman Empire was among the first to buildand maintain an extensive paved road system, linking its empire together. Many thought such a feat impossible, but theRoman nevertheless attempted it, and indeed, some of the roads they built are still in use today!

Perhaps the greatest example though of the innate human tendency to expand and explore is illustrated by the EuropeanAge of Exploration. This era is characterized by fleets of ships, staffed with hard, adventurous men, sailing off into theunknown waters of the western world. Common knowledge of that day was that if you sailed to far west, you would beattacked by giant sea serpents. Or, if you were lucky enough to avoid them, you would still fall off the edge of the Earth!Nevertheless, these men were willing to risk their lives for the adventure and riches that the unknown offered.

It has now been several hundred years since the Age of Discovery. With the help of satellites, we have mapped nearlyevery crack and crevice on the face of the Earth. The adventure that people once found in sailing off on ships to thewest has become common place. However, there is another frontier, one that humans have just recently opened up andone that offers the greatest challenge and promise that humanity has ever faced. That frontier is space, and the first mostlikely candidate of human exploration is the planet Mars. The reason the planet Mars is most likely the next object ofour exploitive efforts in the next century is that humans by nature are colonizers. Trips to the moon are fun andinspiring, but we as a race have rarely been content with just visiting a new place, and then coming right home. We asa race like to expand and settle permanently, and the only planet in the near future on which that is possible is Mars.

– 1 –

Jonathon Smith; email: [email protected]

In the introduction to my senior year world history class, my teacher asked the class, by way of a group discussionquestion, why we should study history. Many interesting ideas were brought up, but the one that fascinated me mostwas the idea that we can use the past to predict the future. History is after all just one big soap opera, with this empirerising and this empire falling, these people attacking those and this person doing that. We can take examples in historythat are comparable to examples today, and then extrapolate what the future might hold by how things turned out withour historical counterpart. Indeed there is much to be learned by examining the past.

When one looks over the various great civilizations in the past, the Greeks stand out as representing an unusually greatflourishing of new ideas. There are many theories as to why this is so. Some historians claim that the harsh countrysideof Greece molded the Greeks into a creative and enterprising people. Says one scholar, “The country, to a large extent,determined the character of its inhabitants. Greece is a land which makes its own terms, and which imposes certainrequirements on those who come to live there.” Others attribute it to a few great men, such as Plato and Aristotle. Bothof these are valid theories, and will be revisited throughout this paper. However, I believe that the primary source ofthis great flourishing of ideas was the Greeks fundamental government structure, that of the independent city-state, orpolis. The nation of Greece was really a collection of thousands of independent governmental units known as polises.Each one of these polises was free to do as it pleased, and therefore many pursued and developed different ideas on amultitude of topics, and the net result was a great flourishing of knowledge.

It is known that a great expansion of knowledge took place in ancient Greece, and it is also pretty firmly understoodhow and why this took place. However, the real question is what will be done with this knowledge? Is it possible thatthis example from the past could be used to set up another great flourishing of knowledge in the future? Thosecircumstances that caused this unusual flowering of knowledge could be recreated to actually induce a second one? Theopportunity to make such an attempt presents itself as humans begin to strike out into space and colonize the planetMars. If development of future Mars colonies is directed in the same way as the Greek city-states, then it stands toreason that the results might be the same, i.e., that Mars colonies could become the source of a second great blossomingof knowledge. For years we have used the past to predict the future. Why not use it to help create the future?

Geography, Geography, GeographyAround 750 BC, small villages located on the Greek peninsula began to organize themselves into city-states. One mightthink it curious that the Greeks chose the Polis type government format as they began to organize politically. Off acrossthe Mediterranean, to their southeast flourished the great Persian Empire, a political body that was blooming andspreading across hundreds of miles. The Mycenaean civilization, which had preceded the Greeks in the Mediterraneanalso, had an empire of sorts, whose power encompassed the Mediterranean for nearly 200 years (Bowra 32). It seemsthat, as examples of political bodies, the Greeks had all about them models of large, far ranging empires. Why then didthe Greeks not seek large unified state encompassing the whole of the Greek peninsula, and instead opt for the smaller,more local city-state government type? The answer in large can be attributed to the geography of Greece and therestrictions it placed on those early villagers.

Greece, despite all its majestic beauty and grandeur, was not a nice place to live back in the time of the early Greeks.The literature describing it is harsh, to say the least. “ . . . A land of hard limestone mountains separated by deep valleys,it is cut almost in two by the narrow divide of the Corinthian Gulf.” (Bowra 12) The country itself is amazingly small,not even as large as the Yemen or Florida(Bowra 12). When this is taken into account with the fact that nearly three-quarters of all the land in Greece is covered with mountainous terrain of the kind described above, you begin to see thesituation of the early Greeks. There were no huge open plains where they might have grown large fields of crops, noconvenient river valleys upon which to build an empire. The peoples of Greece had to content themselves with livingin the narrow spaces between the mountains, where the soil was rich enough to sustain their crops (Bowra 65).

The settlements that developed in these small patches of fertile ground were very much isolated from one another. Theharsh terrain of Greece made communication and travel between these settlements very difficult. As these settlements

– 2 –


grew it became necessary for more political organization. Seeing as it was not feasible to unite with other settlements,each of these settlements started up their own political bodies, and thus the city-state is born in Greece.

The literature describing the geography of Mars is also harsh, to say the least. “. . . The Martian terrain is incrediblyvaried. It includes canyons, chasms, mountains, dried river / lake beds, flood runoff plains, craters, volcanoes, ice-fields, dry-ice fields, and chaotic terrain, to name just a few . . .” (Zubrin 139). Mars has a total surface area of 144million square kilometers, a land area equal to all the usable land surface of Earth. The various features mentionedabove are distributed all throughout the planet, with such famous features as the 4,000 kilometer long Valles-Marineriscanyon system, and also the extinct volcano Olympus Mons, the largest known mountain in the Solar System. Anothervery important aspect of Mars is its atmosphere. Mars has a very thin atmosphere, which exerts only about a hundredthof a percent of the pressure at MSL on Earth. Also, the major component of the atmosphere is Carbon Dioxide, whichmakes up approximately 95.3% of the atmosphere. Also, the mean surface temperature on Mars is -53 degrees Celsius.

This description of Mars makes Greece sound rather mild, geographically speaking. Some considerations should bebrought up, though. The geography of Mars is very similar to that of ancient Greece, with respect to the technologicalsophistication of its settlers and inhabitants. On the surface, the two geographies may seem vastly different, with Marsbeing by far the harsher of the two environments. However, it must be remembered that at the time the Greeks wereestablishing themselves in ancient Greece, there were no airplanes or highways with which to travel from place to place.There were no advanced agricultural equipment or techniques to aid them in their cultivation of fields, and there wereno construction machines to help them build their cities. People traveling to Mars, although Mars is much harsher, willhave technology that will allow them to effectively survive on the surface. The specifics of these technologies will beaddressed later in this paper, but suffice it to say at this point that they do exist. Now, this will not be the easiestexistence, it will be challenging. The whole argument though is that it will be as much a challenge for Mars coloniststo survive in the Martian environment as it was for the Greeks to survive in the harsh environment of Greece.

This similarity is perhaps more easily seen when the effect that the geography has / will have on the colonizers isexamined. We have seen that the harshness and lack of land in ancient Greece served to isolate groups of people intosmall, self-reliant communities. The general ruggedness of the landscape also discouraged travel and communicationbetween the different city-states. The Martian environment requires that some sort of pressurized shelter be built forhumans to live in. This will prove to be a major limiting factor in the size, and hence population, of future Martiancolonies. Restated, the Martian environment will naturally serve to isolate people into small, self-reliant communities.Although communication between these various shelters will not be a problem due to modern advancements in satellitecommunication, travel between these different groups will be difficult. Pressurized rovers or highly expensive trainsystems would be needed for any kind of reliable long-range commuting between colonies. Restated, the geography ofMars will discourage travel between the various colonies. Can you see the parallels?

The same geographic features that kept Greece from developing as a single unified state also served to help protect themfrom being conquered and ruled by a single empire. In the Greeks / Persian War, which constituted the greatest threatto Greek independence, the geography of mainland Greece was perhaps the most powerful ally the Greeks had. Theruggedness of the Greek landscape hindered the movement of the Persian army through Greece, and also madesupplying the army with food and supplies difficult. The seven hundred Greeks fighting at the battle of Thermopylaewere able to use the strategic advantage of the narrow canyon pass to hold back the entire Persian army for almost sevendays. The ruggedness of the Greek landscape in fact discouraged invasion by reputation alone. Potential invadingcountries saw that not only would it be hard to conquer all these little towns placed sporadically among the mountainsand valleys of Greece, but also even if that were managed, effectively enforcing their rule if the conquered city-statestried to rebel would be almost impossible.

Future Martian colonies will also be in a position where external, established powers will find it extremely difficult tomaintain comprehensive control of them. Mars is nearly 134 million miles away from Earth, a six-month journeythrough space, thus any attempt on the part of an Earth-based power to rule any substantial number of colonies on Mars

– 3 –


would be nearly impossible if the colonies did not want to be ruled. If the colonies chose to rebel or ignore orders fromEarth, it would be nearly 6 months before Earth could make any kind of response. Also, rule of all the Martian coloniesby a single Mars-based power would also be difficult, for reasons already discussed. Transportation of humans betweencolonies is so expensive that any kind of large troop movement would not be easily done, therefore rule would beextremely difficult to enforce.

Mars and Greece do have many geographic similarities. These geographic similarities led, in ancient Greece, to the riseof the independent Polis, and in future Mars, will point colonies to developing in the same way, for the same reasons.

MarsThus far we have discussed the similarities between Greece of the past and Mars of the future. The main point of thispaper in many ways relies on using the situation of ancient Greece as a metaphor and projection for what might happensomeday on Mars. Justification has already been put forward as to how these two are related, and it has been establishedto a degree that the two have common geographies and that these geographies have the same effect on the people settlingthem. However, before this discussion can go forward, further justification is needed that there will indeed be a futureMars, i.e., that Mars is capable of being settled by humans, and that it has the necessary allure and resources to sustainpermanent human settlements.

Mars, although extremely harsh environment-wise compared to Earth, has all the raw materials necessary to sustainhuman life. When examining Mars as a possible home for future settlers, the two elements of primary importance areoxygen and water. Fortunately, Mars has a plentiful supply of both, although not in the forms we are used to on Earth.

Mars has an atmosphere composed of 95 % carbon dioxide, 2.7 % nitrogen, 1.6 % argon, and is quite devoid of diatomicoxygen. However, carbon dioxide itself contains two oxygen atoms per carbon-dioxide molecule, and through a processof direct carbon dioxide-reduction, which involves heating the carbon dioxide molecules to 1100’s Celsius, the moleculecan be split into carbon and atmospheric O2 (Zubrin 152). While this method exhibits a fair amount of reliability, it isalso quite energy expensive and probably will not be utilized on a large scale on Mars. The primary source of oxygenwill most likely come be water. Water can be reduced by a process known as electrolysis, into its component parts,hydrogen and atmospheric oxygen. The oxygen can then be utilized for creating breathable air, while the hydrogen, aswe will see, has its own very important uses (Zubrin 151).

If water is to be utilized not only to provide nourishment to settlers, but also to create air for those settlers, Mars mustbe able to provide a more than abundant source of it. Luckily, Mars does not disappoint. However, Mars has no oceansor flowing streams, so where will all this water be coming from? There are actually several different sources of wateron Mars. The most convenient and attractive source of water to a Mars settlement would be an underwater spring, ageothermally preserved pocket of water inside the Martian crust. A colony or water distribution station would situateitself directly on top of or near to an underwater well of water. This water would then be pumped up for use in thecolony, and would most likely also be packed as ice for export to other colonies. While these underwater stores of waterhave not been directly observed on Mars, there is good reason to believe they exist. Earth has hundreds upon hundredsof underground springs, and there is no reason to believe that the same isn’t true of Mars. Other sources of water that,although not as convenient as a geothermal spring, would provide water in the bulk necessary to sustain colonies aresubsurface ice deposits, above surface ice deposits (for colonies located far enough north for above ground ice to existin bulk), and directly from permafrost soil (Zubrin 185).

Mars contains the basic substances necessary for human survival, oxygen and water; that has been established.However, if Mars ever hopes to be home to colonies of human settlers, it must be able to offer an existence beyond justbarely surviving. Simply mining air and water on Mars may be enough for early precursor missions to the red planet,but if colonies are ever to thrive, they must be able to develop large industries and agricultural centers. It would not bepractical for these industries to import all their raw material and so forth, due to the high costs of transporting off-planetmaterials to Mars. Thus, materials, which would support large-scale industrial and agricultural projects, must be

– 4 –


available on Mars if we ever hope to successfully colonize there. Once again, Mars does not disappoint. The most easilyaccessible and abundant industrial products on Mars are iron and carbon. An oxidized form of iron known as hematite,covers the surface of Mars and is actually the substance that gives Mars its red color. Extracting pure iron from thehematite is no novel procedure and has been used on Earth from the time of the first iron weapons. Carbon dioxide isthe primary component of the atmosphere on Mars. Methods of extracting oxygen from carbon dioxide have alreadybeen discussed, and as we have seen, leave free carbon as a by-product.

It may have already occurred to you that these two elements, iron and carbon, are the primary components inmanufacturing steel. With an initial investment in reactors and furnaces, an infrastructure can be set up on Mars thatwill allow steel to be produced for relatively low cost. The importance of this infrastructure alone cannot be overemphasized. The ability to produce steel means the ability to produce large-scale construction projects and the abilityto provide a diverse number of industries with an important manufacturing material.

Steel is not the only metal of importance that can be produced on Mars however. Elements such as copper, silicon andaluminum are also postulated to be available in relative abundance on Mars. Methods for extracting and refining theseminerals, as well as producing other products such as plastics, ceramics, glass, and fertilizer, are discussed in great depthin the book, The Case for Mars, written by Robert Zubrin. All the specific methods employed will not be covered inthis paper, but suffice it to say that it is possible to produce them.

So, we have seen that Mars not only houses the primary necessities of life, but also contains all the raw materialsnecessary to sustain large-scale human colonies and industry. The only question that remains is whether or not we havethe technology to make all this work; whether or not we have the know-how to set up settlements and utilize the rawmaterials present on Mars to make colonization practical. The answer to this question is both yes and no.

Right now humans possess the technology to mount a short-term humans-to-Mars exploration program. We have thenecessary launch capabilities and technologies to send a small crew to Mars and return them safely to Earth. Althoughthere has been much theoretical work done in the area, we do not at present possess the technological sophistication toset up a permanent human colony on Mars. However, this is to be expected, and should not be viewed in any way as adiscouraging thing. Much of the activities of the early human missions to Mars will be centered on exploring ways fordoing things on Mars. They will work to set up a cache of actual experience in dealing with the Martian environmentand will perfect the techniques that have only been theoretically explored thus far. For instance, at this point in time,crops have never been successfully raised on Mars. Now while there is a lot of theoretical work on how this could bedone, until humans actually go there and test it out, it can not be substantially stated that humans possess the technologyto raise crops on Mars. The other main technological areas that these early missions will center on developing are thesciences of processing Martian resources into usable forms, and building structures on Mars using indigenous Martianresources. All three of these areas have comparable counterparts on Earth, and thus we have only to take what we havelearned on Earth and modify it to work in the Martian environment. This will not be an easy task, but it will not be sodifficult as to prevent humans from settling the red planet.

GreeceChapter two was justification for comparing Ancient Greece to future Mars. It was support that such a comparison isnot out of context. Chapter three was to show the feasibility and strong possibility that the colonization of Mars willtake place, that this whole discussion is not about just some fantasy idea that never has a chance to come to fruition.Both of these were needed to set the stage for the grit concept of this paper; the great experiment that happened inGreece, and how we can set up the same flourishing of knowledge to happen on Mars.

Something unusual happened in the nation of Greece, something that had never happened before, something that onlythe recent rise of science and technology in the western world can compare too. The Greeks were not an especiallywealthy group of people. The nation of Greece itself is rather small, both in size and population, as we have alreadyseen. They were not genetically superior in any special way, or any kind of super human race. Yet, the Greeks of the

– 5 –


mid-millennium before Christ single-handedly managed to advance civilization over a thousand years. The Greeksmade breakthroughs, not simply discoveries, but true breakthroughs, in nearly every aspect of human inquiry, frompolitics, to economics, to philosophy, to science, to aesthetics. The Greeks revolutionized thought on all aspects ofhuman existence, and the ideas they originated have been and are being practiced by every nation on Earth, in one wayor another. To understand this great flourishing of knowledge in ancient Greece and what made it possible, it isnecessary to understand the basic governmental unit of the ancient Greeks: the Polis.

Richard Hooker, world cultural expert, explains the development of the Polis.

The single greatest political innovation of the ancient Greeks was the establishment of the polis, or city-state. In the Mycenean age, the Greeks lived in small, war-oriented kingdoms, but for reasons unknownto us, they abandoned their cities and their kingdoms sometime between 1200 and 1100 BC. From thatpoint onwards, they lived in either sedentary or nomadic tribal groups; the period is called the GreekDark Ages and lasted until sometime between 800 and 700 BC. The tribal or clan units of the dark agesslowly grew into larger political units at the end of this period; beginning around 800 BC, trade beganto dramatically accelerate between the peoples of Greece. Marketplaces grew up in Greek villages andcommunities began to gather together into large defensive units, building fortifications to use incommon. On this foundation, the Greek-speaking people who lived on the Greek peninsula, themainland, and the coast of Asia Minor, developed political units that were centrally based on a singlecity. These city-states were independent states that controlled a limited amount of territory surroundingthe state. The largest of these city-states, for instance, was Sparta, which controlled more than 3000square miles of surrounding territory.

The overwhelming characteristic of the city-state was its small size; this allowed for a certain amountof experimentation in its political structure. The age of the city-state in Greece is an age of dynamicand continual experimentation with political structures; this period of experimentation gave theEuropean world most of its available political structures. Its small size also allowed for democracy,since individual city-states were small enough that the free male citizens constituted a body smallenough to make policy decisions relatively efficiently. The overwhelming importance of the polis in theevolution of European political structures is betrayed by the word “political” itself: derived from theword polis, “political” etymologically means “of or relating to the polis.”

— (Hooker)

The key statement in the above quote is, “The overwhelming characteristic of the city-state was its small size; thisallowed for a certain amount of experimentation in its political structure.” Not only did the small size of the city-stateallow for experimentation in the political style of the city, but it also allowed for a wide range of cultural and scientificexperimentation. But before this train of though is pursued, some examples of the contributions of the Greeks will begiven. It is easy to state that the Greeks advanced civilization a thousand years, but further evidence is needed to givethat statement merit. So before it is explained how the city-state set the stage for this blossoming of knowledge andculture, it will first be substantiated that there in fact was a blossoming of knowledge and culture. If you are alreadyfamiliar with the many contributions of the Greeks, you may wish to merely skim through or even skip over thefollowing section, seeing as it is pretty extensive. It is essential to the purpose of this paper, though, that this informationbe given.

It is probably in the political arena that the Greeks made their most influential discoveries to the world. As stated byMr. Hooker, “this period of experimentation gave the European world most of its available political structures.” Perhapsthe political system most easily drawn back to Greece is democracy, and its place of origin, Athens.

Athens has achieved great fame in the western world for being the “birth place of democracy.” Democracy had its startin Athens in 503 BC, with Cleisthenes. While Cleisthenes was Chief Archon in Athens, he initiated political reforms

– 6 –


that were vital to the development of democracy there. Cleisthenes’ reforms were meant to bring “isonomia,” that is,equality before the law of all citizens, a further step toward democracy. The reforms started by Cleisthenes finally cameto their full fruition in 462 BC, when Ephialtes, also acting as Chief Archon, increased the power of the AthenianAssembly (the democratic power of Athens) beyond that of any other political party. (Chronological) This is generallyconsidered to be the true start of democracy in Athens.

The Athenian Assembly was the main law making institution in Athens, and it was composed of every free, maleAthenian over the age of thirty. The Assembles deliberations were made more manageable by the work of a smallercouncil. The council itself had 500 members elected from out of the assembly, fifty chosen to represent each of the tenAttic tribes. The council prepared an agenda and list of proceedings for the general assembly. The council, althoughsmaller than the general assembly, was really too large to manage the day-to-day tasks of government, so another innercouncil of fifty men was elected from out of the council for this job. The inner council served as the main-directgovernmental administrator for the democratic city-state of Athens (Bowra 93).

The democracy that was begun in Athens does not much resemble our modern day notions of a democratic government.Still, Athens was the first government of any magnitude to actually put democratic principles into play. It was the first testbed of democratic ideas the world had, and thus is credited with being the source of the democratic system of government.

The Athenian democracy was not the standard in ancient Greece; rather it was the exception. The majority of city-statesin Greece had a form of government known as an oligarchy, which simply means “rule by few.” The variety in structureand format of these oligarchic governments varied largely between the different city-states. In some cities, the wealthyheld the real political power, and thus there was a wealth oligarchy, known as a timocracy (Hooker). In others it wasthe artisans, or philosophers. Or in others, like Sparta, it was the military that held all the power.

Sifting through all these different governments, one finds aspects of communism, socialism, fascism, monarchialism,and many other government types. Such a fact is hardly surprising when one really grasps that there were literallyhundreds of these little city-states, all with different government types, being ruled independently, however they pleased.There may not have been city-states that were “all-communist” or “all-socialist,” but these many city-states were thefirst to really take these different governmental ideas for a test ride, to see how they actually worked in the real world.They may not have originated all the ideas themselves, but they were the first to test them out with real life experience.

The Greeks contributed a lot to the field of politics, but it was by no means the only area to which they contributed. TheGreeks have been renowned for centuries for their intellectual inquiries into philosophy.

There had been many established religious and philosophic systems before the time of the Greeks. However, the Greeksconstituted the first large-scale emergence of rationalistic beliefs, and thus their philosophic contributions are largely inthe realm of rational inquires into the nature of the world and the humans living in it.

Rationalism, for what ever its value, appears to have emerged from mythology with the Greeks. In engaging in thisintellectual exercise, the Greeks assumed, of course, that nature would play fair; that, if attacked in the proper manner,it would yield its secrets and would not change position or attitude in mid-play. Over two thousand years later, AlbertEinstein expressed this feeling when he said, “God may be subtle, but He is not malicious.” There was also the feelingthat the natural laws, when found, would be comprehensible. This Greek optimism has never entirely left the humanrace (Wilson Pre-Socratic).

Thales, born in 624 BC in the city-state of Miletus, was the first of the Greek philosophers, and arguably the greatest ofthe pre-Socratic philosophers. He is the first man we know of to have asked the question, “Of what is the universemade?” He postulated himself that the fundamental element of the universe was water, and that the Earth itself wasnothing more than a flat disc floating on an infinite ocean. This theory has long since been proven false, but it was neverhis answer that was important to the area of philosophy. Rather, it was the question that he posed that would be his

– 7 –


legacy, for it would be the basis for the work of all the Greek naturalistic philosophers to come for the next hundredyears (Wilson Pre-Socratic).

The three great patriarchs of Greek philosophy and, without argue, the most famous of the Greek philosophers, wereSocrates, Plato and Aristotle.

Socrates was born in Athens in 470 BC. He spent most of his life roaming the streets and marketplaces of Athens,talking with those who would talk with him, and trying to set people strait in their erroneous thinking. He is theoriginator of the Socratic style of teaching, that is, of teaching someone by leading him or her, through intenseconversation, to arrive on their own at the conclusion you want them too (Gaarder 65). His philosophic project was oneof getting the Athenian citizens to examine their life in respect to philosophy, to step back and see the bigger picture.Socrates commanded a large following among the youth of Athens. Among his disciples was a young man who wouldlater even surpass his master in fame – the philosopher Plato.

All that we know about Socrates actually comes through the writings of Plato. Plato, who was born in Athens around427 BC, wrote a series of dialogues to expound upon his philosophic ideas. In most of these dialogues, Plato usedSocrates as his main character, and this is the source of all our information about Socrates. Plato was convinced thatthe world as we see it is really just a shadow of reality, that behind every object in the physical realm there existedsomewhere an ideal form of that object, which was perfect and flawless in every way. Plato said the only way we couldever come to really grasp what these ideal objects might be like is through the use of our faculty of reason (Gaarder82)(Wilson Plato). Plato also had a student who would one day rival him in fame and intellectual prowess, Aristotle.

Aristotle was born in Stagira, which was a province of northern Greece, in 384 BC. As a young man he traveled toAthens where he enrolled in Plato’s Academy. He excelled there and was even reported by Plato himself to be “theintelligence of the school.” Aristotle based all of his philosophic and scientific conjectures on his experiences directlywith reality. He believed that the physical realm was the only objective base humans had for gaining knowledge, andthat a fact was only a fact if it could be empirically reduced to a physical observation. This constituted Aristotle’sgreatest contribution to philosophy, this idea which was in direct opposition to Plato’s theory of Ideals, but which wouldlater become the basis for modern science (Wilson Aristotle).

Aristotle also did a great deal to advance science. Aside from being a philosopher, he was also an excellent fieldresearcher, and pretty much single-handedly started the field of biology. However, he was only one of many, manyGreeks to make major advancements in the sciences.

The Greeks were very imaginative people, and a natural wonder that very much captivated their interest was the sky thatrevealed itself as night fell. The Greeks were fascinated by the stars and moon and planets, and hence, one of the areasof their greatest contributions to science was astronomy.

Around 370 BC, there lived a talented Greek astronomer named Euxodus of Cnidus. He developed a mechanical systemto explain the movement of the planets, in which he placed the Earth at the center of the universe with everything elserevolving around it. Although we now know this to be incorrect, it still represents a tremendous theoretical exercise inmathematics and astronomy (Ancient Astronomy).

Eratosthenes, born in 276 BC, was a diversely educated man. His major contribution to the sciences was that hemanaged to calculate the circumference of the Earth with remarkable accuracy. He is also remembered for his workwith prime numbers (O’Connor Erotosthenes) (Ancient Astronomy).

Hipparchus, who was born around 140 BC, was an excellent astronomer. During his life, he classifieds the stars intogroups based on their apparent brightness, estimated the size and distance of the moon, found a way to predict eclipses,as well as calculate the length of the year to within six and a half minutes (Ancient Astronomy).

– 8 –


Another Greek astronomer who made great advancements to the field was Heraclides of Pontus. He proposed that theseemingly westward movement of stars in the sky was actually caused by the eastward rotation of the Earth. He wasalso among the first astronomers to advocate a more heliocentric theory of the universe. He taught that Venus andMercury rotated around the sun, not the Earth (Ancient Astronomy).

The Greeks also made advancements in the field of Medicine, although not as in depth as in astronomy. The mostprominent Greek physician in history was definitely Hippocrates of Cos. Hippocrates is known as the “Father ofMedicine,” and rightfully so. He made scientific explorations into nearly every field of medicine including surgery ingeneral, bone fractures, ulcers, head injuries, and even hemorrhoids. He is also known for his work in the field of bio-ethics. The Hippocratic Oath, a code of ethics by which a physician should conduct himself, is still required to be takenby aspiring physicians to this day (Hippocrates).

Much of the information gathered by Greeks in the fields of astronomy and medicine, although extremely important andsignificant in their own right, have become somewhat outdated in the present day and age. However, the advancementsmade by the Greeks in Mathematics have served as the foundation upon which all modern math has been developed,and indeed much of what the Greeks worked out nearly 2000 years ago is still in everyday use.

The well-known trigonometric formula known as the Pythagorean theorem is a good example of this. The Pythagoreantheorem is named after its developer, the Greek philosopher / mathematician, Pythagoras of Samos.

Pythagoras was born in 582 BC on the Aegean island of Samos. As a young man he departed Samos for the southernItalian peninsula known as Croton, then under Greek control. There he was to found his famous cult known asPythagoreanism. Although very mystical in belief and practice, this cult also very much revered the study of mathematicsand science. In particular, Pythagoras was intrigued with numbers. He attributed almost divine importance to numbers,and saw them as a way to understand the universe. He was the first man known of to understand the relationship betweenthe length of a string on a musical instrument and the note it produced, and computed the ratios between string length andpitch. He was also very interested in irrational numbers; that is, numbers that cannot be expressed as a fraction but ratherkeep repeating as a decimal (an example is the number denoted by Pi) (Wilson Pre-Socratic).

Zeno of Elea, born about 450 BC, is another great Greek mathematician. Zeno combined mathematics and logic to comeup with some strange theories. One of his stranger theories was that motion is impossible –” he argued that motion isimpossible: If a body moves from A to B then before it reaches B it passes through the mid-point, say B1 of AB. Now to

move to B1 it must first reach the mid-point B2 of A B1. Continue this argument to see that A must move through an

infinite number of distances and so cannot move.” (O’Connor The Rise)

Archimedes, born in the mid 2nd century BC, made significant contributions to the field that would later be termed ascalculus. Among other things, Archimedes, using a rudimentary form of integration known as exhaustion, was able tocalculate the surface areas of circles, cones, ellipses and parabolas (O’Connor The Rise).

There has been much discussion of the great intellectual achievements of the Greeks, about their scientific andphilosophic and mathematical discoveries. However, that is only half the story of the ancient Greeks. The Greeks hadvery demanding intelligences, but also commanded vast and creative imaginations, and made many significantcontributions to the arts. Perhaps the most lasting and influential of the Greek arts was their creative writings.

Almost every school child has heard the story of the goose that laid golden eggs or the fox and the grapes. These arepart of a collection of short stories that have come to be collectively known as Aesops fables, named after their author,Aesop of Samos. Aesop was a Greek slave who lived in the early 6th century BC. His stories, although somewhatsimple and straightforward, all have a deeper message, alluding to some vice or virtue of mankind, otherwise known asa moral (Ancient Literature).

– 9 –


Aeschylus, also known as the father of tragic drama, was the earliest of the three great Greek dramatists. Aeschylus iscredited with being the first dramatist to introduce a second main character. All previous drama had used a single maincharacter supported by a chorus. However, by introducing another main character, a more personal and potent dramacould be developed in his stories. He is credited with producing some 90 dramatic plays, only seven of which havesurvived to the modern day. Among these are Agamemnon, Choefori and Eumenides, collectively known as the Oresteiatrilogy (Ancient Literature).

Aristophanes was the greatest of the Greek comedic play writes. He developed a biting style of comedy, known as “oldcomedy,” which centered on comedically criticizing political and social abuses. He is credited with having written 54plays, only 11 of which have survived to the modern day. These include the Clouds, The Frogs, The Knights, Lysistrata,Peace, and Plutus (Ancient Literature).

The Greeks were not only writers, but also very gifted in the art of sculpting. They pretty much invented the art ofsculpting life-like, fluid sculptures. Their style very much departed from the old Egyptian tradition of large, blockystructures, and tended to focus more on movement and action. Their art also had more humanist overtones than thoseof previous civilizations did; the Greeks didn’t only sculpt living things in movement, they sculpted living man inmovement. The creations of Greek artists such as Myron and Polykleitos inspired artists for thousands of years to come.Indeed, not only did roman art reflect the tradition set by the Greeks, but even sculptures as late as the Renaissance, suchas Michelangelo, based their works of the Greek tradition.(Classical Sculpture)

From democracy to sculpting and everything in-between, the Greeks managed to revolutionize the world view of peopleduring and after their time. The debt that modern man owes to the Greeks for their contributions is almostunfathomable; indeed, the Greeks molded the bricks and set the foundation upon which we have been building a towerof knowledge since the time of the renaissance.

So there was a great blossoming of knowledge in ancient Greece, this has been established. How exactly does the city-state tie in, though? To return to the previous statement made by Richard Hooker, “The overwhelming characteristic ofthe city-state was its small size; this allowed for a certain amount of experimentation in its political structure.” It is truethat the small size of the city-state allowed for experimentation in the political structure of the state, but that is not thewhole story. The opportunity the city-state opened up for different political systems to emerge and be tested out alsoapplied to cultural developments. Just as an area that is dominated by a single political power will not be able toexperiment politically, so an area that is dominated by a pervading culture will find it exceedingly difficult to departfrom that path. What the small, local city-state governments provided to the Greeks were small pockets of civilizationthat were not controlled by a larger, national culture. It provided small kingdoms where there were not any set-in-stonebeliefs and doctrines about the natural world, or how art was to be done, a place where enterprising Greeks could taketheir new ideas for a test run. And as we have seen, the Greeks did just that.

You may think that the democratic style of government in use by the United States currently offers the same options asthe city-state did, that it allows for the free, uninhibited development of ideas. “Why do you need a polis,” you mightask, “when you have the U.S.?” While the US does stand for freedom and liberty, the one thing it doesn’t offer is theuninhibited testing of new ideas.

The clearest way to illustrate this is to look back at England during the time the Americas were being colonized. At thattime in history, England was a world power with a long and illustrious history, a history dominated by the monarchy andaristocracy. The England of this time was very established, with a long tradition of how to carry out the function ofgovernment, of how to implement justice, of how to fight wars, etc. While this served to aid England in maintaining itsstatus as a world power, it also served to stifle the development of new ideas. Just as one cannot pour more water intoa full glass, one also cannot implement new ideas into a culture that has pre-existing established traditions.

– 10 –


It was also at this time that English citizens who were tired of the old traditions began making the journey from Englandto the New World. In North America, these colonists found freezing temperatures, starvation, scurvy, and any numberof other hardships, but they also found a land without an established tradition. They found a vacuum of power andculture that they had the opportunity to fill in their own unique ways. The greatest result of this was the establishmentof the United States in 1776, signified by the ratification of a constitution that been the product, not of English tradition,but the rational minds of American settlers.

While the United States of the present bears little resemblance to England of the 16th century, the same basic principlesare still at work. The US has a very established tradition of rule and culture. It has been dominated for over 200 yearsby concept of rule-by-democracy and the Judeo-Christian ethic. The United States is, for all purposes, a full glass. Ithas an established culture with little room for change. An example of this is the ineffectiveness of Socialist andCommunists interest groups in the United States. There have been groups actively promoting the transformation of theUS government to a socialist or communist type government for over 70 years. The ideas of these groups clash,however, with the prevailing political and cultural ideas of the US, and therefore they have found only limited footingin the US. Only in a land lacking established cultural and political ideas can humans really be free to experiment withnew ideas of this nature.

The Greek city-states provided such an opportunity to the early Greeks. Although the Greeks did have common historictraditions in the area of religion, these beliefs were more fairy-tale like, and did not necessarily dictate any specificphilosophic tradition or ethic to them. Each separate state was like an open shell, waiting to be filled with the cultureand political institution that its residence desired, whether it be right or wrong, good or bad, beneficial or harmful. Thisallowed Greeks in general, a great amount of freedom to experiment with different ideas, and allowed specific Greekssuch as those mentioned previously, to develop new and never before seen ideas on science and philosophy andaesthetics. There was a void to be filled in ancient Greece, and the Greeks filled it in fascinating and diverse ways.

This flourishing of knowledge in ancient Greece has been termed by some scholars as the “Greek Experiment.” Besidesbeing a catchy name, this term as applied to the situation in ancient Greece is actually very appropriate. An experiment,as defined by Webster’s New World Dictionary, is “a test or trial of something; specifically, any action or processdesigned to find out whether something is effective, workable, valid, etc.” An experiment is an action taken to find outwhether an idea really fits with reality or not. What made the situation in ancient Greece so amazing and beneficial tohuman kind at large was that, not only were they able to originate many different ideas and concepts in the areas of politicsand philosophy, etc., but they were also able to put these ideas into actual use and test them out. It was like a giantexperiment, where each separate city-state adopted a different set of political and cultural beliefs, and then tested themout. The contribution of the Greeks was not only the production of ideas, but also an example of how those ideas actuallyworked in reality. The Greeks were not only great men of the mind, who were able to invent new theoretical ways ofdoing things, but they were also men of action, who had the proclivity to put their new ideas into use in the real world.

Mars As GreeceThis flourishing of knowledge in Greece was special. It only worked because the conditions were right bothgeographically and politically, that led to the development of the Polis, and that in turn set the stage for the GreekExperiment. Now, we have seen that Mars shares many of the same characteristics as those of ancient Greece. Is itpossible, then, that by playing with the factors involving the colonization of Mars, we could, in effect, set ourselves upfor another type of Greek experiment, but this time on Mars?

The thought that such a possibility exists is both exciting and enticing, but how might one go about doing this? The keyis to let Martian colonies develop as independent political units. In ancient Greece, the colonies were left to make uptheir own society and politics, they were not dictated to by foreign powers, or throttled by the tyrannical rule of a singleGrecian dictator. Each colony was left to work out its own society and politics, and we have seen the result. The keyto setting up a similar Martian experiment is to allow colonies to rule themselves as independent city-states.

– 11 –


This may not exactly be possible on the get go of Mars colonization, and for a very simple reason. The initialcolonization of Mars will be very, very expensive. The establishment of colonies will require huge amounts of capitol,such that only large corporations or governments will be able to finance them. The factors involved in setting up acolony are very complicated, and would take a number of years to complete. First, a corporation or government agencywould have to come up with mission plan, or perhaps more importantly, a charter, in which they would extensivelydescribe the entire mission, including all mechanical systems, a time line for completion and a cost estimate. Then theymust get this approved, and appropriate funding. Then the long and extensive process would begin in which themechanical systems are contracted and built and tested out on Earth. These systems must then be transported at greatexpense to the surface of Mars, and landed at a designated site. Parallel to the construction of the colonies’ mechanicalsystems would be the selection process of the colonists. These people would most likely have to be cross-trained andfamiliarized with the mechanical systems of the colony, and then, again at great expense, transported to the Martiansurface. Then comes the difficult task of setting up the colony and achieving self-sufficiency; i.e., erecting the actualstructure, setting up an industrial infrastructure, getting the agricultural system running reliably.

Needless to say, after investing the amount of money and capitol necessary to establish a colony on Mars, thecorporation or government sponsor will not likely give up control of that colony. They will want to maintain a presencein its governing, and rightfully so. It is also conceivable that certain large corporations may be interested in setting upcolonies for a specific, economic purpose. If large amounts of precious ore or other valuable materials are discoveredon Mars, it may be economically profitable to set up a mining colony. In such a case, the colony would surely bemanaged as just a division of that company.

Colonies created under these circumstances would in all likelihood remain under the immediate control of their sponsor.If that is in the best interest of the world or these colonies is irrelevant; the reality is simply that such a sponsor wouldnot relinquish control of such a major investment. How then will independent colonies come to exist on Mars?

The first colonies will be expensive because they will be the fountainheads. They will need to develop the newtechnology; they will need to figure out how to transport masses of humans to mars; they will need to establish newmethods of working in the Martian environment; and most importantly, they will have to figure out all the little bugsthat are sure to arise in every step of the colonization process. However, once the method of putting colonies on Marsbecomes more routine, and the technologies used become more robust and efficient, then the price tag associated withMars mission will inevitably decrease. When a new and novel technology is introduced to a market, it starts off veryexpensive. However, as better methods are found to do the same job, the cost of the technology is driven down. Thishas happened with almost every high-grade technology produced in the last fifty years, including personal computers,cell phones, home entertainment devices, etc. The same pattern will also happen in relation to Mars colonization. Asthe price for setting up a colony on Mars decreases, it will become possible for independent groups of people to sponsortheir own way to Mars. There are two primary ways in which this will most likely take place.

The first is the sponsorship of a colony by a large space-related organization. Space societies of the future, analogousto the modern day Planetary Society or National Space Society may choose to use member funds to sponsor anindependent Martian colony, as such a feat becomes feasible. Member support for such an activity will most likely behigh, for what loftier goal could a space society ascribe to than to establish an extra-planetary colony. Even moremember support could be elicited if the colony members would be chosen from among the qualified people within thesociety. While the sponsor in this case would still want to maintain ties to the colony, actual administration of the colonywould almost assuredly be left up to the chosen colonists.

While sponsorship by space-oriented societies will be a means by which independent Martian colonies will be created,it nonetheless remains very limited in scope. The bulk of independent Martian colonies will most likely be what I havetermed “communal colonies.” In the communal colony scenario, a charter is issued via-the Internet or some communalcolony corporation saying that a Martian colony is to be formed with a certain number of colonists. There is a pricequoted, per person, for joining the expedition and becoming a colonist. If a person has sufficient sums, he can sign up

– 12 –


on the charter as a colonist. This would continue until the quota of colonists was filled, at which point the fundscollected from the colonists would be enough to establish the colony, and the whole group would take off for Mars.Thus, in the communal colony scenario, each colonist buys his own way to Mars.

While the price of establishing colonies on Mars may decrease, it will most likely never be an inexpensive venture. Thecost each individual would have to pay to join in a communal colony will therefore be very expensive. It may rangefrom a couple hundred thousand to millions of dollars per person. However, while such fees are very expensive, theyare not unfeasibly expensive. Even if the price were as high as two million dollars per person, there would surely stillbe people who would have the economic clout and desire to join the charter. It is not too unrealistic to imagine a personselling all of his possessions on Earth, such as his house and car, to finance his way to Mars. The same thing was doneall the time in the old U.S., with people moving west. It is also conceivable that an extended family may wish to supportan enterprising nephew or son with the funds to join such an expedition. Or perhaps organizations might offer to paythe charter fee as reward for certain student contests, similar to present day student scholarships. Or perhaps there wouldbe Entrance Fee lotteries, where thousands of people would buy tickets, and the winning person would be provided withthe funds to join the expedition. In any case, it is conceivable and probable that if such a charter were issued, even if itwas expensive, there would be enough people with the funding to fill it.

These are the two most probable ways in which independent colonies will come to exist on Mars. Perhaps the countriesor corporations sponsoring the first of the colonies will be willing to take a back seat and relinquish control of thecolonies the colonists; maybe other ways for establishing independent colonies on Mars will be developed in the future.In any case, though, free Martian colonies have the potential to exist.

With the establishment of free colonies on Mars, the stage will be set for a Martian experiment. Initially, most of thefree colonies will probably very much resemble each other, and will probably be run in a way similar to governmentson Earth. However, as time progresses and the colonies begin to face different challenges and opportunities, each willstart to develop in its own unique way, adapting and changing to meet the new requirements placed on it. Hopefullycolonists of these independent states will seize the opportunity to try out new political systems. These future colonistswill have the freedom and opportunity to actually do what others have only dreamed about; to take from Earth the bestit has to offer, and build a new society based on those ideals, leaving behind all the bad. The governments of Earth areto immersed in their own tradition to be able to objectively evaluate themselves, and are to hopelessly caught in theirown cultural rut to ever make any kind of true change. For this to happen, humans must start anew, and we will havethe opportunity on an independent, polis oriented Mars.

The new developments on Mars will not, by any means, be limited to the area of politics. The Martian environment iscompletely and utterly alien to the environment of Earth. People living there will be forced to deal with challenges thathumans have never, in the whole of history, had to deal with before. Such a situation will most definitely bring out aningenuity in the colonists; an ingenuity that will be necessary for their survival. Coupled with the almost unlimitedfreedom the polis has to offer, this environment by all rights should be perfect for the flourishing of new scientific andtechnological ideas.

Just as the Greek peninsula molded the Greeks into enterprising and ingenious people, so will Mars with its colonists.And just as the Greeks, when allowed the freedom to meet these challenges in their own way, came up with an almostlimitless set of ingenious solutions, so will the future settlers of Mars.

References1. Ancient Greek Astronomy http://members.tripod.com/~JFrazz9/astr.html2. Ancient Greek Literature. http://www.hol.gr/greece/ancwords.htm3. Bowra, C.M.. Classical Greece. Time Inc, 19654. Chronological History of Greece in the Vth and IVth centuries BC. http://phd.evansville.edu/tools/chrono.htm5. Classical Greek Sculpture http://harpy.uccs.edu/greek/classicalsc.html6. Gaarder, Jostein. Sophies World. H. Aschehoug & Co, 1991

– 13 –


7. Hooker, Richard. Ancient Greece. http://www.wsu.edu/~dee/GREECE/GREECE.HTM8. Hippocrates, father of Medicine. http://www.hol.gr/greece/medicine.htm9. O’Connor and Robertson. The rise of the calculus.http://www-groups.dcs.st-and.ac.uk/%7Ehistory/HistTopics/The_rise_of_calculus.html

10. O’Connor and Robertson. Eratosthenes of Cyrene. http://www-groups.dcs.st-and.ac.uk/history/Mathematicians/Eratosthenes.html11. Wilson, Fred L. Aristotle. http://www.rit.edu/~flwstv/aristotle1.html12. Wilson, Fred L. Plato. http://www.rit.edu/~flwstv/plato.html13. Wilson, Fred L.. Pre-Socratic Philosophers. http://www.rit.edu/~flwstv/presocratic.html14. Zubrin, Robert. The Case For Mars. New York, New York: The Free Press, 1996

– 14 –


Rabbits On Mars: One Giant Leap

Thomas Gangale[1999]

AbstractIt goes without saying that permanent human settlements on Mars will need to grow their own crops, and there is aconsiderable body of literature that speaks to these issues. The need for farm animals should also be investigated.

While human waste will certainly be used to fertilize the Martian regolith, it also presents health concerns that will eitherneed to be addressed by sewage treatment systems, or by exposure to the ambient environment, in order to eliminatepathogens. Sewage treatments systems will be expensive to transport, and an unknown period of exposure to Martianconditions will be required to render human waste safe for reuse. Selection of an animal species to accompany humansto Mars could address these concerns. The optimum Martian farm animal will have the following characteristics:

1. is well-characterized under laboratory conditions.2. is small, and is therefore easy and inexpensive to transport to Mars.3. has a short gestation period and a high number of births per pregnancy, therefore breeds rapidly from a small initial stock.4. produces good quality manure.5. requires low maintenance (fastidious, self-cleaning).6. consumes most of the vegetable material that is inedible to humans, thereby accelerating the composting process

and reducing the need for biomass processing equipment.7. poses a near-zero health risk to humans.

These qualities describe Oryctolagus cuniculus, the European or domestic rabbit.

This presentation briefly reviews the history of the rabbit in space flight and suggests a program of future missions tostudy its adaptability to powered flight, microgravity and Mars gravity. Possible roles for the rabbit in Mars colonizationare discussed. Preliminary results of experimentation with growing food in Mars soil simulant JSC Mars-1 enhancedwith rabbit feces are also reported.

Characterization

– 1 –

Thomas Gangale; 430 Pinewood Drive, San Rafael, CA 94903; email: [email protected]; web: http://www.martiana.org

The European or domestic rabbit, and in particular the New Zealand White breed, is of course ubiquitous in researchlaboratories. Its physiology is well characterized in reference texts (Harkness &Wagner), (Weisbroth), (Hillyer), as isits behavior both in the wild (Lockley) and in the home (Harriman). The huge volume of baseline data is one factor thatmakes the rabbit an attractive subject for study in space.

HistoryOn 19 August 1960, the Soviet Union launched an unmanned Vostok precursor mission known as Korabl Sputnik 2.Aboard were a gray rabbit, two dogs, 40 mice, 2 rats, 15 flasks of fruit flies, and plants. The spacecraft was recoveredafter 26 hours. This was the first recovery of the Vostok program; indeed, it was the first recovery of a Soviet spacecraft.The rabbit and other passengers were the first life forms ever to return from Earth orbit. So far, I have been unable tofind reference to any other space flights involving rabbits. It would seem that this field of study is wide open.

The Great RecyclerRabbits can play a significant role in rapidly introducing biomass to theMartian regolith and developing fertile soil. Rabbits consume most of thevegetable material that is inedible to humans. The cecum, which is theblind end of the colon, contains symbiotic microorganisms that producecellulase to break down the cellulose walls of plant cells (McLaughlin).Undigested fiber and waste (hard fecal pellets) pass through the largeintestine along with vitamin-rich cecotropes (soft cecal pellets), whichare formed from fermented cecal material (Cheeke). Processing thisbiomass in the gut of the rabbit will reduce the need for mechanicalsystems to support similar functions. The less equipment we drag alongto Mars, or the less we need to operate and repair it, the better.

Take, for instance, a grain crop such as oat. We humans just eat the insideof the seeds. Rabbits eat the whole plant.

– 2 –


Low Cost, High Return

At and average mass of about 3 kilograms, the rabbit is one of the smallest of domesticated mammals. Thus, rabbitsand associated support equipment and supplies can be launched at probably about an order of magnitude less cost thanmore conventional farm animals such as cattle, sheep, and swine. Furthermore, only a small number of rabbits will beneeded to start a colony on Mars. The ability of rabbits to proliferate is proverbial, but let’s do the numbers.

Harkness & Wagner gives the average litter as seven to eight, while Weisbroth, et al., puts the average litter size as sixto seven for a large number of breeds. Harkness & Wagner give the optimal breeding age as being between four-and-a-half months and three years. While the average gestation period is 31 to 32 days, so that theoretically one doe couldhave 11 litters in a year, Harkness & Wagner states that “an intensive breeding program, requiring good management,will result in up to 8 litters per doe per year.” Also, Harkness & Wagner gives 47% as the ratio of females born per litter,while Weisbroth, et al, cites a study in which 48.6% females were obtained.

Allowing for some infant mortality and the slightly lower number of females born compared to males, the average littershould produce three females which will reach maturity. With the average litter being born at one-and-a-half monthintervals, these females will take three such cycles to mature and will themselves produce litters beginning with thefourth cycle.

Thus, were one to begin with one unneutered male and one unspayed female rabbit on January 1, one would have a litter ofthree females and three males in early February, for a total of eight rabbits, including the parents. There would be another litterof six by the end of March, another in mid-May, and still another by the end of June, for a total of 26 rabbits. At this point, thethree females from the first litter are ready to breed along with their mother, and so the four females will produce 24 rabbits inAugust, for a total of 50 rabbits.

Now the three females from the second litter mature, joining their mother and three older sisters, and the seven femalesproduce 42 rabbits by the end of September, for a total of 92 rabbits. By November ten females are producing litters,adding 60 new babies to the population, for a total of 152. Finally, by the end of December, 13 females will give birthto 78 bunnies, swelling the population to 230 at the end of the first year.

Please don’t try this at home!

Now, this numbers game started with just a single breeding pair. Obviously, to ensure a robust gene pool, we wouldtake a few more rabbits than that to Mars. The important point is that the short gestation period and high birth rate perpregnancy greatly leverages the launch mass allocated to establishing this species on Mars.

– 3 –


Low Health Risk of HumansThere are very few diseases that rabbits can transmit to humans,and these are virtually unheard of in domestic populations.Standard quarantine procedures prior to launch will assure that adisease-free population is transported to Mars.

One human health concern is allergic reaction. Typically thismanifests in the form of upper respiratory symptoms, but inmany cases these symptoms should be controllable throughmedication.

Another concern is the potential for rabbits to inflict wounds onhumans. Contrary to popular belief, they are not just harmlesslittle bunnies. They can be aggressive. As with anyrelationship, there must be understanding and trust betweenhumans and rabbits. In any case, rabbit bites and scratches canhardly be considered a dire threat, and there might be a case tobe made for the occasional low-level stressing of the humanimmune system in maintaining long term health.

High Companionship ValueWith regard to interaction with humans, the natural behavior of the rabbit gives it several advantages over other animalsthat might be considered for transplantation on Mars.

Rabbits are very fastidious. They groom themselves and each other. Thus their scent is inoffensive to humans. Rabbitsare quiet. They don’t bark, howl, meow, moo, crow, or cackle. This is an important consideration, since humans andrabbits will live together in close quarters.

Rabbits are affectionate. Like humans, they are social animals, and have an instinctive need for companionship. Thenumber of pets that are maintained in urban and suburban households throughout the world, for no other reason than forcompanionship, eloquently bespeaks the human emotional need to have animals around us. They are part of our naturalenvironment. The growing practice of pet therapy in nursing homes and other institutions is further evidence of theimportance of animals to the emotional health of humans living in conditions of isolation.

Project LEPUSNow, I will return to my central hypothesis that rabbits can significantly aid in the development of fertile Martian soil.In March of this year, I began experimenting with growing food in 17 kg of Mars soil simulant JSC Mars-1 enhancedwith rabbit feces. I have dubbed this experiment the Lagomorph Environmental Processing Utility Study, or LEPUS.

First of all, I would like to introduce the crew. My wife Gail and I have rescued over 200 abandoned rabbits since 1992,and have placed about 70% of them for adoption in permanent homes (for more information on Bunny Hill, please visit:http://members.xoom.com/mars_ultor/rabbits/html/rabbits.htm).

Madeline and Tiger are New Zealand Whites who were abandoned in San Francisco in 1998. A few days after theywere rescued, Madeline gave birth to seven bunnies, but because they were transported to our house under conditionsthat allowed the babies to get too cold, five of them died the first night. Gail and I named the two surviving bunniesScully and Mulder.

I have two sets of experiments running. The first set consists of three identical containers, each with a soil depth of 6cm and surface dimensions of 33 x 33 cm. The planters contain: 1) commercially available potting soil, 2) unmodified

– 4 –


JSC Mars-1, and 3) rabbit-enhanced JSC Mars-1. Rabbit droppings are normally hard, encapsulated spheroids of fibrousmaterial, which take some time to break down and mix with soil. I artificially accelerated this process by shredding thematerial in my kitchen blender . . . you might want to keep that in mind if you ever come over to my place for frozenmargaritas. Well, as I said, rabbits present a near-zero health risk to humans. When I mixed the shredded rabbit feceswith the JSC Mars-1, the change in the physical character of the soil was dramatic: rich, fluffy, aerated soil, as opposedto dense, fine sand. It certainly looked and felt like a good growth medium.

All three soils were exposed to rain over a three-week period prior to planting. The unmodified JSC Mars-1 packeddown hard like beach sand in the tidal zone. The rabbit-enhanced JSC Mars-1, however, retained much of its aeration.

Planted in the first experimental set were:• tomato• radish• carrot• onion• peas

It turns out that I grossly underestimated how much volume the rabbit feces added to the JSC Mars-1 (it was only 1,740g, but bulky), so I had to remove approximately one-third of the rabbit-enhanced JSC Mars-1 to get back to the samevolume as the other two samples. I used this surplus material to experiment with other vegetables, with potting soil asa control, but without pristine JSC Mars-1 for comparison. Planted in the second experimental set were a white potatoand eight garlic cloves. The two containers in this set were ceramic bowls 33 cm in diameter by 12 cm deep.

– 5 –


I planted Sets 1 and 2 on 24 March 1999. The image shown above was recorded on 12 April. None of the vegetablesthat were planted from seed germinated well in any of the soils, but it should be noted that the weather was consistentlycooler than normal due to La Niña conditions, and that the soils were in shadow for much of the daytime due to theheight of the containers.

On 17 April I planted Roma tomato seedlings in Set 1. The next image was recorded on 24 June.

The superior performance of the rabbit-enhanced JSC Mars-1 can be seen clearly. The tomato plant in this soil is severaltimes larger than the plants in the unmodified JSC Mars-1 and the potting soil. On this date, the first tomato fruit wasobserved in the rabbit-enhanced JSC Mars-1. The first fully developed pea pods were also harvested from rabbit-enhanced JSC Mars-1 on 24 June. The garlic plants in rabbit-enhanced JSC Mars-1 are noticeably larger than in pottingsoil. I didn’t expect potatoes to flourish in such small containers, and indeed, after 42 days the plant in rabbit-enhancedJSC Mars-1 shows little growth, but the potato in potting soil died during this time. In all soils, some of the carrots Ihad planted on 24 March were just getting started. Again, this is a testament to the unusually cool spring.

In early July, sustained daytime temperatures in excess 40 degrees Celsius severely damaged the plants in theexperiment; however, the tomato plants continued to produce. Of course, temperatures in this range would not be aconcern on Mars.

The following table shows the results obtained so far:

– 6 –


Crop Yields as of 1 September 1999 (grams)

So far, it looks like rabbit stuff has the “right stuff.”

Lessons LearnedThe experiment containers were set up 25 cm above ground to isolate them from weeds and garden pests. This causeda problem with excessive drainage, so that it was difficult to keep the experiments properly hydrated during the hotsummer weather. The experimental setup will need to be redesigned for 2000.

Also, in the case of the first experimental set, the depth of the containers, relative to the small amount of soil used,resulted in excessive shadowing which inhibited growth in the early stages. At the same time, one must bear in mindthat crops on Mars will be exposed to much weaker sunlight than on Earth.

Finally, the dense packing of hydrated pristine JSC Mars-1 may inhibit root development. In follow-on experiments, theperformance of pristine JSC Mars-1 should be compared with that of samples which include a non-nutrient amendment.

Future PlansIf the rabbit-enhanced JSC Mars-1 continues to show promise, humane experiments including rabbits themselves willbe in order.

A rabbit population should be maintained in constant exposure to simulated Martian regolith to test for health effects.A follow-on phase of this experiment should incorporate results from the Mars Environmental CompatibilityAssessment (MECA).

A space flight program should be developed to study the adaptability of the rabbit to the environmental conditions ofvarious phases of a Mars mission, including powered flight, microgravity, and Mars gravity. At this time, I envision ashuttle-launched, shuttle-retrievable MarsRabSat that would either deploy or inflate to a large-diameter toroid and spinto simulate 0.38 g. In addition to video recording rabbit behavior under Mars gravity conditions, the long-term effectof 0.38 g on rabbit physiology could be studied upon retrieval. Such a mission would be a significant predictor of humanphysiological adaptability to Mars gravity, and could also serve as a precursor for a larger manned facility.

Possible Role of the Rabbit in Later Stages of Mars ColonizationIt should be noted that rabbits burrow underground in the wild. On Mars, this behavior will reduce their exposure totwo of the problematic conditions of the Martian environment: radiation and cold. Because of the rabbit’s short periodfrom conception to sexual maturity, the combination of selective breeding and genetic engineering should allow therapid development of a breed that would be able to survive in successively low-pressure environments. This suggeststhe possibility of releasing a Mars-conditioned rabbit subspecies – Oryctolagus cuniculus martianus – into the wilds ofMars at an earlier stage of ecopoesis (terraforming) than other mammal species.

– 7 –


Someday, our descendants may go for a walk in a park, and see a red rabbit sitting under a redwood tree, on a planetthat isn’t so red anymore.

References1. Cheeke, P. R., “Digestive Physiology,” pp. 20-32 in Rabbit Feeding and Nutrition, Academic Press, Orlando, FL, 1987.2. Harkness, John E., and Wagner, Joseph E., The Biology and Medicine of Rabbits and Rodents, 2nd Ed., Lea & Febiger, Philadelphia, 19833. Harriman, Marinell, House Rabbit Handbook: How to Live With an Urban Rabbit, 3rd Ed., Drollery Press, Alameda, 19954. Hillyer, Elizabeth V., and Queensberry, Katherine E., Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, W.B. Saunders Co.,

Philadelphia, 19975. Lockley, R. M., The Private Life of the Rabbit, Macmillan, New York, 1964.6. McLaughlin, C. A., and Chiasson, R. B., Laboratory Anatomy of the Rabbit, 3rd ed., William C. Brown Publishers, Dubuque, IA, 1990.7. Sakaguchi, E., “Fibre digestion and digesta retention from different physical forms of the feed in the rabbit,” Comparative Biochemistry and

Physiology, 102A, no. 3: 559-63, 1992.8. Weisbroth, Steven H., et al., The Biology of the Laboratory Rabbit, Academic Press, New York, 1974

– 8 –


Real-Time Television Quality Full Motion Video for Mars Missions

John F. McGowan III[2000]

AbstractNeither manned landings nor short-range robotic probes such as Mars Pathfinder can explore the surface of Mars, 144million square kilometers comprising as much surface area as all the continents and islands on Earth. Completeexploration of Mars to find or conclusively rule out important discoveries such as past or present life will require high-speed low-altitude or ground-based probes such as airplanes, balloons, or high-speed rovers. These devices will needhigh frame-rate imaging, such as digital video, to explore the planet and for remote operation either by astronauts onMars or mission control on Earth. A variety of uses for video on Mars are presented. Previous results including thesize, weight, power, bit rate, and bit error rate requirements for a video system using commercial off the shelfInternational Organization for Standardization (ISO) MPEG-1 or MPEG-2 digital video compression standardtechnology are reviewed. A significant concern unique to Mars and space missions is that radiation, especially singleevent latchup, may require fabrication of video encoder chips in radiation hardened semiconductor processes. In thispaper, the feasibility of fabricating an MPEG-1 or MPEG-2 video encoder in a current radiation hardenedComplementary Metal Oxide Semiconductor (CMOS) semiconductor process technology is demonstrated. The nearEarth uses of these compact, lightweight, low-power, digital video systems are also discussed.

IntroductionA desirable goal for missions to Mars is real-time or near real-time video coverage of the missions. Video coverage ofrobotic or manned missions will help build and maintain public support for missions to Mars and other space missions.This probably represents the most important and best recognized use of video for space missions. In addition, video canhelp achieve and may even be essential for a large number of scientific and engineering goals during missions.

Video may prove essential for life detection by robotic missions. Experience has shown that unambiguous detection ofpast or present life where it is not expected is difficult. For example, the Viking Lander Labeled Release experimentsproduced positive signals at both landing sites.1 However, these results were eventually interpreted by most planetaryscientists as the results of inorganic oxidants in the Martian soil. Similarly the current controversies over the Martianmeteorites and the past controversies over biomarkers in carbonaceous chondrites such as the Murchison meteoriteillustrate the difficulty of unambiguously identifying life. In the case of microbial life, even a detailed still image of asingle-celled organism might be interpreted as an inorganic structure of some kind. A microscope with a video cameracould observe microscopic organisms dividing or making copies of themselves in real-time. A video camera could alsoobserve microscopic organisms swimming or crawling about in culture. A video of microscopic organisms reproducingwould probably be accepted as unequivocal evidence of life. Video could also reveal exotic life based on biochemistrysubstantially different from terrestrial biochemistry.

Video may also be helpful for engineering goals such as failure analysis and failure prevention. Video of the risky finalapproach and landing of probes should be helpful in understanding failures. A camera or cameras mounted on a landercould unambiguously determine the cause of a failed landing such as the Mars Polar Lander. Cameras mounted on theinterior or exterior of a probe could perform frequent inspections of the probe during the long journey from Earth toMars. A camera could determine the relative location of the edge of Mars and the fixed stars during the final approachto the planet. The probe or mission control might be able to use this to determine if the probe is coming in too low asin the loss of the Mars Climate Orbiter (MCO) or too high.

Neither manned landings nor short-range robotic probes such as Mars Pathfinder can explore the surface of Mars, 144million square kilometers comprising as much surface area as all the continents and islands on Earth.2 Completeexploration of Mars to find or conclusively rule out important discoveries such as past or present life will require high-

– 1 –

John F. McGowan III; NASA Ames Research Center, MS 233-18, Moffett Field, CA 94035-10000

speed low-altitude or ground-based probes such as airplanes, balloons, or high-speed rovers. These devices will benefitfrom high frame-rate imaging, such as digital video, to explore the planet and for remote operation either by astronautson Mars or mission control on Earth.

Video is better suited than a series of slightly overlapping still images to detect and observe transient phenomena suchas dust storms, lightning, releases of sub-surface gases or liquids, and so forth. Video provides multiple successiveimages from differing viewing and lighting angles that should assist in understanding ambiguous surface features.

Ideally, the exploration of Mars or other planets should seek “something interesting” such as past or present life, geologyrelevant to terrestrial concerns, or unusual physical phenomena. Some features would be obvious even in a series ofslightly overlapping still images. Seepage or venting of fluids or gases from beneath the surface seems like the mostlikely discovery on Mars and might be difficult to detect or study in still images.

On Mars, video should be useful in detecting and studying transient or dynamic phenomena such as dust storms, dustdevils, and lightning in the atmosphere. Seeps of subsurface gases or liquids may occur on Mars. Mars containssubstantial evidence of past volcanic activity including several apparently extinct volcanoes. Current volcanic orseismic activity may produce various releases of gases or liquids and other dynamic processes. Evidence of geologicallyrecent seepage of groundwater has been reported.3 If Mars possesses subsurface water or ice, surface seepage oreruptions of water or steam, even geysers or hot springs in volcanic regions, are possible. Geysers and hot springs havebeen proposed as possible sites for the origin of life on Earth.

The subsurface lithoautotrophic microbial ecosystem (SLiME) in the Columbia River Basalt Group is frequentlysuggested as a model of current subsurface life on Mars.4 This ecosystem produces significant amounts of methane.Natural gas was produced commercially at the Columbia River Basalt Group early in the twentieth century. A sub-surfaceecosystem similar to the Columbia River Basalt Group is likely to produce seepage of methane at the surface. In general,the most likely signature of subsurface life at the Martian surface would be surface seeps of gases or possibly liquids.

Conventional theory holds that the largest, by mass and volume, identifiable trace of past life on Earth are subsurfacedeposits of oil, natural gas, and other hydrocarbons. Oil is attributed to simple single-celled organisms trapped insediments and pressure cooked over several million years.5,6 If Mars was once warm and wet, supporting lakes andoceans with primitive microorganisms, Mars may possess subsurface deposits of oil and natural gas. These would causeseepage of oil and gas, especially methane at the surface of Mars. While trace gas detectors probably offer the greatestchance of detecting seeps of subsurface gases, video can assist in detecting and studying these dynamic phenomena.7Many gases of interest such as methane are transparent to visible light and could only be detected indirectly in the visiblespectrum. An infrared video camera may be able to detect and observe releases of gas or fluids that would be invisibleto a visible light camera, especially since gases or liquids from deep within the planet are likely to be warmer than thesurface of the planet.

Although current animal life on Mars seems extremely unlikely, video would be better able to detect and identifyanimals than still images, especially if the animals are well camouflaged or small. Similarly, video will be better suitedfor detecting a variety of unanticipated transient phenomena on Mars or other planets. These exotic possibilities includenew physical phenomena and mobile probes from extraterrestrial civilizations.

Video technologies for Mars pose a challenge because of the limited power, volume, and total weight of systems thatcan be transported to Mars, especially for robotic missions, the possible vulnerability of video systems to the harsh spaceenvironment, the large bit rate requirements of digital video, and the high bit error rates of deep space communicationlinks. Video systems in Earth orbit share many of these challenges.

Video technologies for Mars have been previously studied for a proposed mission to Mars to fly a small airplane downthe Valles Marineris canyon. This study concluded that a video system based on the International Organization for

– 2 –


Standardization (ISO)’s MPEG digital video compression standard could be built with a total weight of 2 Kg includingheavy shielding, a size of about 800 cm3, and a power dissipation of 20 Watts or less.8 MPEG (Motion Pictures ExpertsGroup) digital video at 352 pixels by 240 pixels, 30 frames per second, requires a bit rate of one megabit per second.9The bit error rate requirement is 10-6. A video system of this type typically causes a peak signal to noise ratio (PSNR)of about 30 dB between the compressed image and the original uncompressed 352 by 240 pixel frame. The proposedvideo system consisted of a camera lens or lenses, a CCD or other imaging array, and a video processing system tocompress the digital video for transmission back to Earth.

Table 1. Mars Video System Parameters

MPEG digital video at 352 by 240 pixels, 30 frames per second, with a bit rate of one megabit per second is about thelowest subjective video quality that viewers find acceptable. The 352 by 240 pixel, 30 frames per second, video formatis known as SIF for Source Input Format. Video with dimensions of 176 by 120 is known as Quarter SIF or QSIF.MPEG-1 SIF digital video is sometimes referred to as “VCR quality.” MPEG-2 digital video at 720 by 480 pixels and30 frames per second requires about 6-8 megabits per second.10 This is good digital video quality and is used routinelyin DVD’s (Digital Versatile Discs) and other consumer digital video products. This is sometimes referred to as “Studio”or “Broadcast” quality. An MPEG-2 digital video system for Mars would have the same size, weight, and powerrequirements as the MPEG-1 system if commercial off the shelf (COTS) components can be used. The bit raterequirement would be 6-8 megabits per second.

The principal obstacle to video for Mars missions appears to be the low bit rates currently possible over communicationslinks between Mars and Earth. These have been less than 100 kilobits per second when the satellites have line of sightfrom Mars to Earth. This may be resolved by establishment of communications relay satellites in Mars orbit. TheNASA Jet Propulsion Laboratory is considering a variety of communication relay satellite networks in Mars orbits withprojected bit rates of 1-10 megabits per second.11,12

Although essential for thorough exploration of Mars, communication relays are infrastructure and do not provide animmediate tangible return on investment. Thus, generating support for funding communication relay systems can bedifficult. It is much easier to justify a relay if it performs some other function such as planetary exploration. Indeed, todate all relays sent to Mars have been part of planetary exploration probes with still image cameras such as the MarsGlobal Surveyor. A high bandwidth relay satellite may carry the first video system to Mars to observe the Martian duststorms and seek other transient phenomena. In addition to entertainment value, this may be useful for formulatingGlobal Circulation Models (GCM) of the Martian atmosphere.

Digital video on robotic missions to Mars may be significantly affected by the mechanical stability of the platforms.Digital video compression technologies such as MPEG digital video use compression methods such as motionestimation and frame differencing that may be degraded by jitter in the camera from frame to frame. An airplane or

– 3 –


balloon may experience jitter due to turbulence in the Martian atmosphere and limitations of the aerobot’s guidance andcontrol systems. A rover will be traversing a rocky surface. Mobile probes must provide sufficient mechanical stabilityfor digital video compression to work efficiently.

Missions to the Valles Marineris canyon on Mars, a popular proposed destination for Mars missions, may suffer frommultipath interference effects. Signals sent by the probe back to a relay or directly to Earth will also bounce off thecanyon walls or floor, interfering with the primary signal. This can cause serious problems for communications;especially compressed digital video signals, which are highly susceptible to, lost data.

The radiation issues for Mars missions including Mars orbiters are much less severe than Earth orbit. Mars lacks asignificant magnetic field and has no radiation belts, unlike Earth. Typical total ionizing dose for Mars missions is 10-20 Krads. It is likely that shielding such as an aluminum case can protect against Total Ionizing Dose (TID) effectsduring Mars missions. The primary concern is single event effects from high energy Galactic Cosmic Rays (GCR) thatcan penetrate any shielding. Single event upsets (SEU) could be detected using embedded monitoring hardware orsoftware that could reset the video encoder or other hardware as needed. Single event latchup, however, canpermanently damage a video-processing chip. This seems to be the largest radiation concern and could force the use ofradiation hardened Complimentary Metal Oxide Semiconductor (CMOS) even for a Mars mission.

Commercial applications including the Internet, computing, entertainment, surveillance, and medical video are steadilydriving video technologies toward lower power, lighter weight, and higher levels of integration on a single chip, higherquality, and higher compression ratios for the same perceived video quality. Mobile and other wireless applications mustaddress many of the same noisy channel and mechanical robustness issues as space missions. However, radiation is nota significant issue on Earth. Radiation hardening and some other space-hardening issues such as extreme temperaturesmay require custom development of video encoders or cameras.

MPEG digital video is highly sensitive to uncorrected errors. MPEG makes heavy use of variable length codes to achievehigh compression. A single-bit error can cause loss of synchronization between the encoder and the bitstream or thebitstream and the decoder. In the worst case, a single bit error can cause the loss of a half-second of MPEG digital video.This happens when a single bit error causes loss of synchronization early in the MPEG I frame, the key frame used bythe motion estimation and compensation. All the frames until the next key frame are encoded or decoded improperly.

The synchronization problem due to the variable length codes is one of the main reasons that MPEG hardware encoderand decoder design is especially sensitive to timing errors such as clock skew. There is very limited tolerance for errorssince the effects of errors are not localized spatially or temporally if synchronization is lost. Thus, porting a workingcommercial bulk CMOS MPEG chip design to radiation hardened CMOS, where the signal timing will be different, maybe difficult.

The problems with variable length codes over noisy communications channels have been extensively studied for mobileand wireless video applications on Earth. Several methods exist to modify the variable length codes without addingsignificant overhead to avoid the loss of synchronization and reduce the impact of uncorrected errors. These methodsare not incorporated in the MPEG-1 or MPEG-2 standards. One method, reversible variable length codes (RVLC), hasbeen incorporated in the ISO MPEG-4 and ITU-T (International Telecommunications Union – Radio Sector) H.263+digital video standards.

Thus, video technologies for Mars and other space missions may encounter some special conditions not reproduced incommercial applications on Earth. The most worrisome is that missions to Mars or other space missions may require aradiation hardened video encoder. Below it is demonstrated that MPEG video encoders can be fabricated in currentradiation hardened CMOS technologies. No advances in radiation hardened CMOS semiconductor process technologiesare required.

– 4 –


Radiation Hardened MPEG EncodersDeveloping or porting a Very Large Scale Integration (VLSI) chip design for an MPEG digital video encoder is adifficult project with substantial schedule risk. It is not uncommon for MPEG digital video encoders to fail during thefirst chip fabrication requiring revision of the design and fabrication of a second-generation chip. According to someexperts, roughly half of all Application Specific Integrated Circuits (ASIC’s) fail on the first attempt, in many casesrequiring fabrication of a revised design.13 Since Mars missions have a narrow launch window to Mars, difficulties infabricating a working radiation hardened chip can easily delay a mission by years if digital video is deemed essentialfor the mission. Consequently, the use of Commercial Off- the- Shelf (COTS) components, probably repackaged forspace, is preferred. However, the radiation hazards, especially single event latchup, may force fabrication of an MPEGor other digital video encoder in radiation hardened CMOS.

Unfortunately, radiation hardened semiconductor processes consistently lag a few generations behind commercial bulkCMOS semiconductor processes in system clock rates, levels of integration, and power requirements. Thus, while manysingle chip MPEG-2 Main Profile at Main Level (720 by 480 pixels, 30 frames per second, 4:2:0 and even 4:2:2 videoformat) video encoders in commercial bulk CMOS exist, there does not appear to be a single radiation hardened MPEGor other digital video encoder chip. However, it appears that radiation hardened CMOS semiconductor processes haverecently achieved the clocks speeds and levels of integration required for a compact, lightweight digital video system.

Table 2 lists the relevant parameters of a number of commercial video encoders. Unless otherwise noted, these aresingle chip encoders. The size of the design is given in transistors or logic gates as quoted in the product literature. Theindustry standard is that a single two input NAND logic gate uses four (4) transistors. Thus, a chip using one milliontransistors corresponds to 250,000 logic gates. Some caution should be applied in using two input NAND gates toconvert between transistors and logic gates. MPEG-1 and MPEG-2 digital video encoders are not constructed from two-input NAND gates.

Most MPEG-1 and MPEG-2 video encoders process ITU-R 601 (formerly CCIR-601) uncompressed digital videowhich has a clock rate of 13.5 MHz. Thus, the clock speeds of video encoders are typically multiples of 13.5 such as27 MHz, 54 MHz, and 81 MHz. A minimum clock speed of 13.5 MHz is required simply to keep up with the ITU-R601 input signal.

Table 2. Commercial MPEG Video Encoders

– 5 –


– 6 –


It is possible to make an MPEG-2 Main Profile at Main Level (720 by 480 pixels at 30 fps) video encoder with aninternal clock rate of 54 MHz and 3-5 million transistors. An MPEG-1 SIF (352 by 240 pixels at 30 fps) video encoderprobably can be manufactured with an internal clock rate of 27 MHz and about one million transistors.

Table 3 lists the relevant parameters of leading radiation hardened CMOS processes. These numbers should be takenwith caution. Numbers of usable gates for gate arrays are often optimistic. These numbers may be derived by dividingthe number of available transistors by 4, the number of transistors in the standard two input NAND gate. However,MPEG and other digital video encoders are not arrays of NAND gates and may require more transistors per logic gate.

Table 3. Radiation Hardened CMOS Semiconductor Processes

It appears possible to fabricate an MPEG-2 or MPEG-1 digital video encoder in current radiation hardened CMOSprocesses. For example, it appears that an MPEG-2 Main Profile at Main Level video encoder could be fabricated usingHoneywell’s RICMOS-V SOI process in one or two chips. The power requirement would be about 5 watts. Chips canbe integrated into multichip modules to reduce mass and volume requirements. Packages largely determine the mass

– 7 –


and volume of chips. The worst case would probably be five (5) chips with a power requirement of 5 watts. Thisassumes that Honeywell’s figures for usable gates are substantially over-optimistic for an MPEG digital video encoder.

Radiation-hardened CMOS semiconductor process technologies have recently achieved the system clock rates andlevels of integration necessary to implement MPEG video encoders and other video components on a few chips or asingle chip. It should be possible to build and fly compact, lightweight video systems to Mars and near Earth in the nextfew years even if radiation-hardened silicon is needed.

Near Earth ApplicationsVideo technologies for Mars can be tried out first near Earth where a much larger potential market for video systemsprobably exists. In addition, bit rates are not a restriction. High quality digital video is routinely relayed throughgeosynchronous Earth orbit (GEO) satellites. Consequently, a video system in Earth orbit is highly feasible.

It remains difficult to service satellites in Earth orbit. The Space Shuttle and other manned vehicles appear to be theonly practical means to service orbital systems. This limits the lifetime of most satellites. Robotic servicing systemshave been proposed to extend the lifetime of satellites in Earth orbit. Video cameras on the robots would permit remoteoperation or supervision of the robots in real-time. The remotely operated robots could refuel, repair, and upgradesatellites in orbit.

Video systems in Earth orbit could be used to detect and monitor transient phenomena including the weather, fires,automobile traffic, ship movements, and so forth. Several possible scenarios exist. The simplest would be a single videocamera with a telescope on a geosynchronous satellite. Gyroscopes could be used to orient the camera and trackphenomena on the Earth’s surface. A more complex system would be an array of video cameras and telescopes on asingle geosynchronous satellite.

A more ambitious scenario would be a constellation of low Earth orbit (LEO) satellites providing global coverage. Thiswould require a sophisticated system for pointing the cameras at a target, stabilizing the cameras, and switching fromsatellite to satellite as the moved in and out of observing range. One could envision hundreds of small satellites with asingle camera or a small cluster of cameras in polar orbits providing continuous real-time coverage of the entire planet.LEO satellites would not require as powerful or bulky optics as the GEO satellites.

The Earth could be divided into hexagonal regions. A user would select a hexagon that they wanted to watch. Thenthe system would route the video from the satellite in the constellation above the hexagon. As a satellite entered thehexagon, it would orient its camera toward the selected target in the hexagon or provide a wide-angle view of the entirehexagon. An adjustable mirror might allow the satellite to target a region within the hexagon quickly without expendingmuch energy or reorienting the entire satellite.

ConclusionIt is technically feasible to fabricate a single-chip or few chip MPEG digital video encoder using radiation hardenedCMOS semiconductor processes. Thus, there is no fundamental obstacle to creating compact, lightweight, low powervideo systems for missions to Mars or other space missions.

Historically, full motion television in space has been restricted to special missions such as the manned landings on theMoon, other manned missions, some weather satellites, and probably some classified reconnaissance satellites.43 Theadvances in chip technology discussed in this paper make possible universal television for space missions, includingmissions to Mars.

AcknowledgmentsNASA Ames Research Center assembled a large team to prepare the Mars Airplane proposal that inspired this work. Theauthor thanks all members of this team, especially Julie Pollitt, Julie Schonfeld, Ruben Ramos, and Hiroyuki Kumagai.

– 8 –


The author thanks Andrew B. Watson of the Vision Science and Technology Group at NASA Ames Research Center. Theauthor also thanks his colleagues at the Desktop Video Expert Center − Steve Kyramarios, Mark Allard, Mike Fitzjarrell,Kathy Charland, Steve Sipes, and Joe Flores. This research was supported in part by the Applied Information TechnologyDivision, NASA Ames Research Center and the NASA Research and Education Network (NREN).

References1. Gilbert Levin and Ron Levin, “Liquid water and life on Mars,” Proceedings of the SPIE 3441, pp. 30-43, 19982. Robert Zubrin, “Long Range Mobility on Mars,” Journal of the British Interplanetary Society 45, pp. 203-210, 19923. Michael C. Malin and Kenneth S. Edgett, “Evidence for Recent Groundwater Seepage and Surface Runoff on Mars,” Science 288, pp. 2330 −

2335, 20004. Todd O. Stevens and James P. McKinley, “Lithoautotrophic Microbial Ecosystems in Deep Basalt Aquifers”, Science 270, pp.450-454, 19955. Guy Ourisson, Pierre Albrecht, and Michel Rohmer, “The Microbial Origin of Fossil Fuels”, Scientific American 251(2), pp. 44-51, August 19846. Guy Ourisson, Pierre Albrecht, and Michel Rohmer, “Palaeochemistry and biochemistry of a group of natural products: the hopanoids”, Pure

Applied Chemistry 51, pp. 709-729, 19797. John F. McGowan III, “Oil and natural gas on Mars”, Proceedings of the SPIE 4137, 2000 (in press)8. John F. McGowan, “Video Technologies for Mars”, Proceedings of the Second International Convention of the Mars Society, Univelt

Incorporated, San Diego, 20009. ISO/IEC 11172, Information Technology – Coding of moving pictures and associated audio for digital storage media up to about 1.5 Mbit/s,

International Organization for Standardization (ISO), Geneva, November 199110. ISO/IEC 13818, Information Technology – Generic coding of moving pictures and associated audio information, International Organization

for Standardization (ISO), Geneva, November 199411. Personal communication, Steve Townes, NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 9110912. Rolf C. Hastrup, Robert J. Cesarone, Jeffrey M. Srinivasan, and David D. Morabito, “Mars Comm/Nav MicroSat Network”, 13th AIAA/USU

Conference on Small Satellites, Logan, Utah, August 23-26, SSC99-VII-5,1999 ()13. John Schroeter, Surviving the ASIC Experience, p.5, Prentice Hall, Englewood Cliffs, New Jersey, 199214. Zapex Research Limited, Netanya, Israel ()15. Zapex Research Limited, Netanya, Israel ()16. Winbond, Taipei, Republic of China ()17. iCompression, Santa Clara, California, United States ()18. Yoshiko Hara, “NTT weighs in with single-chip MPEG-2 encoder”, EE Times, October 29, 199819. Mitsuo Ikeda et al, “SuperENC: MPEG-2 Video Encoder Chip”, IEEE Micro, pp. 56-65, July-August 199920. NTT Electronics Corporation, SuperENC product data sheet; personal communication by Gary Webster of NTT Electronics Corporation21. Panasonic (Matsushita Electronics) Single Chip MPEG-2 Video Encoder MN85560 Product Data Sheet22. Masayuki Mizuno et al, “A 1.5-W Single-Chip Video Encoder with Low Power Motion Estimation and Clocking”, IEEE Journal of Solid-

State Electronics 32(11), pp. 1807-1816, November 199723. NEC Corporation (Japan), Single Chip MPEG-2 Video Encoder Product Data Sheet24. Anthony Cataldo, “Video encoders and decoders unveiled at JES”, EE Times, October 9, 199825. Sony Semiconductor Corporation (Japan), “CXD1922Q MPEG-2 Technology White Paper”26. Sony Semiconductor Corporation (Japan), Sony CXD1922Q Video Encoder Data Sheet27. C.T. Chen, T.C. Chen, C. Feng, C.C. Huang, F.C. Jeng, K. Konstantinides, F.H. Lin, M. Smolenski, and E. Haly, “A Single-chip MPEG-2 Video

Encoder/Decoder for Consumer Applications”, Proceedings of the 1999 International Conference on Image Processing (ICIP-99), October 25-28, 1999, Kobe, Japan

28. Stream Machine, “Stream Machine SM2210 MPEG-2 Video Codec Product Brief” ()29. Tiosys Inc., “VICA2000 Product Brief”, ()30. Vision Tech Limited, Herzliya, Israel, “Kfir Technical Specification” ()31. Mitsubishi Electronics America, 1050 East Arques Avenue, Sunnyvale, CA 94086, (408) 730-5900, “Mitsubishi Electronics MPEG-2 Encoder

Chip Set Achieves Main Level at Main Profile Encoding with Maximum of 10 Chips”, Press Release, December 11, 1995 ()32. IBM Corporation, “MPEG-2 Multi-Chip Module Encoder and Decoder Release to Enable VBR Encoding”, Press Release, IBM, 199733. IBM Corporation, “MPEG-2 Real-Time Encoder Chipset”, Press Release, IBM, 199734. Philips Semiconductor, EMPIRE Product Data Sheet35. Albert van der Werf, Fons Bruls, Richard P. Kleihorst, Erwin Waterlander, Math J. W. Verstraelen, and Thomas Friedrich, “I.McIC: A Single-

Chip MPEG-2 Video Encoder for Storage”, IEEE Journal of Solid-State Circuits 32(11), pp. 1817-1823, November 199736. Honeywell Solid State Electronics Center, 12001 State Highway 55, Plymouth, MN 55441, (800) 323-829537. S.T. Liu, W.C. Jenkins, and H.L. Hughes, “Total Dose Radiation Hard 0.35 µm SOI CMOS Technology”, IEEE Transactions on Nuclear

Science 45(6), pp. 2442-2449, December 199838. Personal communication from Tim Bradow of Honeywell, Honeywell Solid State Electronics Center, 12001 State Highway 55, Plymouth, MN

55441, (800) 323-829539. UTMC Microelectronic Systems Inc., 4350 Centennial Boulevard, Colorado Springs, CO 80907, (800) 645-UTMC, UT0.6CRH Commercial

RadHard Gate Array Family Data Sheet40. Personal communication from Vere Butler of UTMC

– 9 –


41. Lockheed Martin Federal Systems, 9500 Godwin Drive, Manassas, VA 20110-4157, 1(800) 325-4019 (x4754), ()42. Personal communication, Richard S. Flores, Sandia National Laboratories, Digital Microcircuit Design, MS 1072/Dept. 1735, P.O. Box 5800,

Albuquerque, NM 87185, (505) 844-7220 ()43. William E. Burrows, This New Ocean, Random House, New York, 1998

– 10 –


Airtight Sealing A Mars Base

William F. Dempster[1999]

AbstractAtmospheric leakage from a Mars base would create a demand for continuous or periodic replenishment. This wouldin turn require extraction or mining for oxygen and other gases from local resources and attendant energy requirementsfor such operations. It therefore becomes a high priority to minimize leakage. This paper quantifies leak rates asdetermined by pressure and the size of holes and discusses the implications of pressure for structural configuration. Theauthor engineered the sealing of Biosphere 2 from which comparisons are drawn.

IntroductionMan has imagined travel to the Moon and planets, and in particular to Mars, for decades. Long term habitation of Marswill require a substantial infrastructure for shelter and production of food. Enclosures for these purposes must retainbreathable atmosphere and limit leakage to rates that can be practically replenished from local resources or resupplyfrom Earth, i.e., to very low leakage rates. Leakage is largely driven by a pressure differential between the inside andoutside of an enclosure. It would be desirable to reduce the pressure to minimize leakage and reduce forces on thestructure, but pressure is needed to support both humans and plants.

Quantification Of Leak RatesHypothetically considering air leakage through a hole in the case where the outside pressure is less than half the insidepressure, the mass flow rate is given by (Mark’s, 1987):

wherem is the mass of gas in the enclosure, kgC is the coefficient of discharge, about 0.6P is the inside pressure, kg/m2

A is the cross-sectional area of the hole, m2

T is the temperature, degrees K

The ideal gas law is

whereV is the volume of the enclosure, m3

n is the number of kilogram-moles of gas in the enclosureR is the ideal gas constant for SI units, 847.8 kg-m/(kgmole-°K) and

whereM is the molecular weight of the gas.

Combining (1) through (3) we obtain a differential equation for P as a function of time, t (seconds)

from which

– 1 –

William F. Dempster; Director of Systems Engineering, Biospheric Design, Inc.; 26 Synergia Road, Santa Fe, NM 87505; Tel. 505 438 9873;Fax 505 474 5269; E-mail: [email protected]

dm/dt = -0.53CPA/√T (1)

PV = nRT (2)

n = m/M (3)

dP/dt = -0.53CPART/(MV√T) (4)

dP/P = -0.53CAR√T/(MV) dt = -269.6A√T/(MV) dt (5)

Integrating, we obtain a decaying pressure in the enclosure

whereP0 is the initial pressure at t = 0 and

and

depends on the area of the hole, the temperature, the molecular weight and the volume of the enclosure.

To get order of magnitude estimates of the leakage impact of small holes on a prospective Mars base we take someassumptions:

A) The average molecular weight of air within the enclosure is approximately 29. (For instance, pure oxygen is 32, purenitrogen is 28; Earth’s atmosphere is 28.96.)

B) The temperature of the air is 18ºC (64.4ºF) or 291ºK.

We are only investigating the order of magnitude of leakage. In this context, the results are not significantly sensitiveto the accuracy of the above assumptions.

We next construct Table 1 showing the percentage of the initial pressure that is lost over a year (t = 31,536,000 seconds)for postulated Mars bases of given atmospheric volume and a single circular hole whose cross sectional area representsthe aggregate area of all holes in the system. One needs to consider what loss rate is acceptable in light of methods ofreplenishing the atmosphere. If one sets an upper limit, for example, of ten-percent loss per year, then we see that thetolerable hole size for, say a 1000 cubic meter Mars base, is less than 1/5 of a millimeter, which would be nearlyinvisible. For a Mars base the size of Biosphere 2 (180,000 cubic meters), less than ten percent per year loss wouldmandate aggregate equivalent hole size no larger than 2 mm diameter.

Comparisons To Biosphere 2The serious implications of even very small holes was recognized in the design and construction of Biosphere 2 whichoperated at an extremely low-pressure differential between inside and outside. The lung system of Biosphere 2 was built

– 2 –


P = P0e-kt (6)

k = 269.6A√T/(MV) (7)

to absorb the expansion/contraction of the atmosphere while keeping the differential pressure less than 8 Pascal (0.08mb or about 1/1000 psi). Testing by manipulating the pressure differential and measuring lung movements determinedthat the aggregate of all holes in Biosphere 2 was equivalent to a single hole about in the range of 13 to 19 mm diameter.The consequent exchange between inside and outside air amounted to between 5% and 10% of the total volume per yeareven with the very high degree of pressure neutralization (Dempster, 1994). The equation of fluid flow at lowdifferential pressures is different than (1) above (Mark’s, 1987; Dempster, 1994).

The primary concept of Biosphere 2’s lung system was to protect the entire structure from explosion or implosion dueto the inevitable pressure differences that develop between the inside and outside of an airtight vessel on Earth as theinside temperature, inside humidity and outside barometric pressure fluctuate. These pressure variations would have farexceeded the Biosphere 2’s strength, and yet they are almost trivial compared to the huge forces tending to explode acontainer in near vacuum which is pressurized to any significant fraction of a standard atmosphere. Because thepressure variations in a Mars base will be very small compared to the absolute pressure, an expansion / contractionsystem analogous to that of Biosphere 2 would be irrelevant on Mars.

Biosphere 2 could not have been sealed without a bottom liner, which was fabricated from 1/8-inch thick stainless steel.A virtually infinite number of leak paths exist through the ground and the requirement for a bottom seal will be evenmore critical for pressurized containment on Mars. A Mars base liner must be robust and, if in direct contact withregolith, tough against abrasion and puncture. The chance of repairing a liner leak of uncertain location perhaps underequipment or infrastructure or tons of plant growth soil with very little time to stem the loss of atmosphere is very slim.Soil provides no significant barrier to airflow on a scale relevant to these concerns.

The possible range of atmospheric pressures and compositions is beyond the scope of this paper, but some generalconsiderations and anecdotal information are offered. As we will see below, the absolute atmospheric pressure hasprofound structural implications and so it becomes desirable to minimize the required pressure. One can consider howmuch margin of extra pressure above an absolute minimum is affordable in terms of mission cost and weight associatedwith the enclosure’s ability to contain the pressure.

It has also been considered that space missions could use an enriched or even pure oxygen atmosphere for human lifesupport at reduced pressures. Provision of an oxygen partial pressure of about 200 mb offers equal oxygen availabilityto what humans experience in Earth’s atmosphere. If the composition were pure oxygen, it would be only about 1/5 ofEarth’s atmospheric pressure. However, the fire hazard associated with enriched or pure oxygen atmospheres isextreme. The fire that claimed the lives of three astronauts in the Apollo 1 accident occurred in a pure oxygenatmosphere. The possibility of spontaneous combustion in enriched oxygen atmospheres is increased. The productivityof plants in various atmospheric compositions and pressures needs to be researched in detail before an acceptableartificial atmosphere for a Mars base can be designed.

Lowered oxygen availability has definite limits for human life support. The well-known slow oxygen decline inBiosphere 2 from 21% to 14.4% over a 16-month period approached the limit before oxygen was injected into the systemto restore the vitality of the eight biospherians (Severinghaus et al, 1994). At 14.4% oxygen and total atmosphericpressure of 880 mb at the Biosphere 2 site (1160 meters or 3800 feet elevation) the oxygen partial pressure was equivalentto Earth’s atmosphere at 4160 meters or 13650 feet elevation. This compares to the highest human settlements.

Replenishment of a mixed gas atmosphere may imply different methods and systems to restore each component. If, forexample, in order to avoid the fire hazard of a pure or highly enriched oxygen atmosphere, nitrogen is designed to bethe most plentiful gas, as it is on Earth, sources of both nitrogen and oxygen are required. Nitrogen is over 2% of Marsatmosphere (Meyer and McKay, 1996) and could possibly be obtained by separation, while oxygen might be obtainedchemically from CO2.

– 3 –


Structural Implications Of PressureTypical habitation structures on Earth need not withstand strong differential pressures on opposite sides of their surfaces.A worst case is probably a building struck by a severe tornado with winds of, say, 300 miles per hour (134 m/s). Sucha storm will destroy most Earth buildings, yet the wind pressure is only about 1120 kg/m2 (230 lbs/ft2). The pressureof a standard atmosphere for comparison is 10330 kg/m2 (2116 lbs/ft2). The ambient atmospheric pressure of Mars isonly about 70 kg/m2 and is negligibly small as a counterbalancing force on the outside walls of a Mars base withpressure adequate to support human life.

Artist’s renderings showing a Mars habitat built as a lightweight, transparent shell greenhouse sitting on the Martiansurface are plentiful but contradict basic pressure considerations. Even assuming an atmosphere reduced to 1/5 standardpressure (which would need to be nearly 100 percent oxygen for human life support and carry attendant fire hazards asnoted above), the force tending to tear it off the Martian surface is extreme. For example, a structure with a 10-meterdiameter circular footprint and 1/5 standard atmosphere would have a total lift of 162,300 kg or 5166 kg per runningmeter of the perimeter, or 5.17 kg per running millimeter of the perimeter. See Fig. 1.

A construction engineer seeking to anchor a perimeter wall against such uplift might drill anchoring bolts into bedrockand set them with epoxy. If bedrock were not available and a perimeter concrete foundation ring were to be used to holdthe edge down by weight, the foundation ring would need be 2.7 meters wide x 2.7 meters deep allowing for Marsgravity. The uplift per running meter of perimeter increases linearly with the overall diameter. This example assumes1/5 standard atmosphere; higher pressures mean proportionally greater uplift.

To try to hold down the structure by loading a flat membrane floor with regolith fill faces the difficulties that the edges wouldpull up unless the floor were stiffened. Conventional construction techniques to stiffen a 10 meter wide floor against thebending forces generated from a 1/5 atmosphere pressure would call for 14-inch deep steel I-beams on 1 foot centers weighingover 300 kg each. Also the fill would need to be 4 meters deep to counteract 1/5 atmosphere. See Figures 2 and 3.

Other structural forms that present difficulties are sharp corners and flat surfaces. A structure with a rectangular footprint,even with a domed roof, will be subject to extreme stresses at the corners because the internal pressure will tend to flexout the right angle at the corners. A flat surface 1 meter x 1 meter resisting 1/5 atmosphere pressure would have to be 6mm thick steel or 21 mm thick glass. If resisting 1 atmosphere, the thicknesses are 13 mm steel or 46 mm glass.

Inflatables with no corners seem much more feasible for their lightweight, compact storage, and easy deployment.However, the stresses must be carefully considered even with inflatables. The least possible tension is when thegeometry is a sphere. See Fig. 4. In our example of a 10-meter diameter sphere and 1/5 atmosphere, the tension at anyequatorial ring is 5.17 kg per running millimeter. If the thickness is, say, 2 mm, the stress is 2.6 kg/mm2 or 3670 lbs/in2.A spherical fabric inflatable to 10 meters diameter and 2 mm thick would weigh approximately 625 kg (taking thedensity of the fabric to be comparable to water). Thicker is stronger, but also heavier.

– 4 –


Key questions are: can a flexible, lightweight material be developed with the required strength (also transparent ortranslucent?) that resists ultraviolet degradation, and is tough against abrasion or puncture? Although the example of 1/5atmosphere is used here, it is by no means assured that such a low pressure is viable considering the implication of highoxygen concentration and associated fire hazard. The forces should all be multiplied by 5 for a standard atmosphere.

On-Earth TestingFortunately there are simple first approximation tests that can be performed on Earth for the concerns raised above.Fabricate a candidate inflatable structure (or rigid structure, for that matter) and pressurize it to one atmosphere gaugepressure or two atmospheres absolute pressure. On Earth this structure is experiencing the same pressure stresses as ifit were at one atmosphere absolute pressure on Mars. If it has significant leaks they will be diagnosed by the loss ofpressure over time. Any gauge pressure, P, on Earth will nearly simulate the absolute pressure P on Mars.

Broader ConsiderationsThe concept of building a greenhouse on Mars suggests that natural light could be sufficient for plant growth. This isa doubtful proposition. In Biosphere 2 the glass superstructure intercepted about 50% of the outside light in one manneror another, whether by absorption or reflection of the glass, by shading of the struts or from shading by side walls orparts of the structure. The net result was that between 45% and 50% of the exterior light was available inside for plantgrowth. This was a serious problem for plant growth at the low light period of winter months and didn’t leave muchextra margin even in summer, which led to the installation of supplementary artificial lights in the agriculture biome ofBiosphere 2 after the initial 2-year closure trial. Mars is 1.52 times further from the sun, and so by the inverse squarelaw, sunlight at the outer edge of its atmosphere is 43% that of Earth. Atmospheric absorption and the absorptionspectrum determine how sunlight intensity at the surface of Mars compares to the surface of Earth. One reference notesMars surface sunlight to be about 60% of Earth’s (Boston, 1988). Further loss will occur getting through the transparentor translucent greenhouse shell.

Maximization of entering sunlight argues for a thin shell. But this also means poor thermal insulation. Multi-layertransparent shells with trapped air between layers are a common approach to insulation but the penalty is additional lossof light at each layer. Typical temperature ranges on Mars may be roughly from -80ºC to 0ºC night to day (-112ºF to32ºF). A greenhouse warmed only by direct solar radiation might only rise above freezing for a few hours on a relativelywarm clear day. A 10m x 20m x 5m high greenhouse with 2 to 4 layers in the shell, artificially heated to internally stayabove freezing in a nighttime ambient -50ºC, would require from 25 to 75 kilowatts continuous heating energy. Amassive warm soil bed can help only partially because the heat will only weakly rise up among the plants without someartificial means of transfer and is also predicated on the soil bed having been thoroughly warmed in advance which willnot happen from sunshine alone. A 10m x 20m vigorously growing planting bed could be enough to support about oneperson based on Biosphere 2 experience.

– 5 –


Exposed surfaces are also exposed to ultraviolet degradation and the effects of windblown sand. Sand abrasion mightlessen sunlight transmission and, if extreme, threaten to wear a hole through the material. All of these considerationstend to support the concept of a deeply buried greenhouse for thermal insulation, protection from sand abrasion and fromultraviolet light as well as radiation hazards for humans. Drawbacks to deep burial are the requirement to dig deep andthe energy demand of artificial lights to grow plants.

Research GoalsNew concepts have been advanced making travel to Mars seem increasingly possible (Zubrin, 1996). This paper mayseem to have presented difficulties that oppose that concept, but, to the contrary, it is intended to focus attention on thechallenges we must overcome to make Mars habitation a reality. A vigorous program to develop the technics ofhabitation on Mars must be created. To this end the following research goals are suggested:

Materials:Create a flexible lightweight completely airtight fabric suitable for inflation to a full atmosphere pressure in largeassemblies. It should be highly resistant to abrasion, puncture and ultraviolet degradation and capable of mountingfittings for airtight electric and fluid penetrations, for viewing windows and airlock doors. It should be able to berepaired simply and quickly in the field while under pressure.

Atmospheric:Develop a broad understanding of what atmospheric pressures and compositions are compatible with vigorous plantgrowth, including genetic variants to further this goal. Develop understanding of the health effects for both humans andanimals of atmospheric pressures and compositions different from those of planet Earth. Investigate fire hazardsassociated with enriched oxygen atmospheres. Develop high efficiency systems to separate Martian atmosphericcomponents and to produce oxygen from atmosphere or other materials found on Mars.

References1. Mark’s Standard Handbook for Mechanical Engineers, 9th ed, edited by E.A. Avallone and T. Baumeister III, McGraw-Hill, 1987, pp.4-22 to 4-23.2. Dempster, William F., Methods for Measurement and Control of Leakage in CELSS and Their Application and Performance in the Biosphere

2 Facility, Advances in Space Research, v.14, no.11, 1994, pp.331-335.3. Severinghaus, Jeffrey P., Broecker, Wallace S., Dempster, William F., MacCallum, Taber and Martin Wahlen, Oxygen Loss in Biosphere 2.

EOS, Trans. American Geophysical Union, v.75, no.03, Jan.18,1994,pp.33,35-37.4. Meyer, Thomas R. and Christopher P. McKay, Using the Resources of Mars for Human Settlement. AAS 95-489. Strategies for Mars, ed. by

Carol R. Stoker and Carter Emmart, Science and Technology Series, v.86, American Astronautical Society, 1996.5. Boston, Penelope J., Mars Mission Life support. AAS 86-177. The NASA Mars Conference, ed.by Duke B. Reiber, Science and Technology

Series, v.71, American Astronautical Society, 1988.6. Zubrin, Robert, The Case For Mars, Simon & Schuster, 1996.

The AuthorWilliam F. Dempster graduated in mathematics and physics from the University of California, Berkeley in 1963 and subsequently worked incomputer programming and systems analysis at Lawrence Berkeley Laboratory. He then participated in the founding of the Institute ofEcotechnics, which helped to establish several projects worldwide integrating ecology and technics in complementary balance. He participated indesign and construction of an ocean-going expedition research vessel which circumnavigates the globe and on which he led a two-year expeditionup the Amazon River. He directed the engineering of Biosphere 2 from 1985 to 1994, invented and designed the expansion chambers called“lungs,” invented one type of airtight glazing system and controlled the development of another glazing system actually used on Biosphere 2. Hedevised and implemented the means of detecting leaks and measuring the leak rate of Biosphere 2. He also determined energy demands ofBiosphere 2, selected equipment and configured systems to meet those demands and demonstrated the certainty of water recycling and the methodsby which the recycled water is collected. He is Director of Systems Engineering for Biospheric Design, Inc. and is involved in planning furtherclosed biospheric systems.

– 6 –


Simulating “Mars on Earth”A Report from FMARS Phase 2

William J. Clancey[2001]

AbstractBy now, everyone who’s heard of the Haughton-Mars Project knows that we travel to Devon Island to learn how peoplewill live and work on Mars. But how do we learn about Mars operations from what happens in the Arctic? We mustdocument our experience – the traverses, life in the hab, instrument deployment, communications, and so on. Then wemust analyze and formally model what happens. In short, while most scientists are studying the crater, other scientistsmust be studying the expedition itself. That’s what I have done in the past four field seasons. I study field science, bothas it naturally occurs at Haughton (unconstrained by a “Mars sim”) and as a constrained experiment using the FlashlineMars Arctic Research Station.

During the second week of July 2001, I lived and worked in the hab as part of the Phase 2 crew of six. Besidesparticipating in all activities, I took many photographs and time lapse video. The result of my work will be a computersimulation of how we lived and worked in the hab. It won’t be a model of particular people or even my own phase perse, but a pastiche that demonstrates (a proof of concept) that we have appropriate tools for simulating the layout of thehab and daily routines followed by the group and individual scientists. Activities – how people spend their time – arethe focus of my observations for building such a simulation model.

The FMARS SimulationThe FMARS simulation is constructed using a tool called Brahms (Clancey et al. 1998; Sierhuis 2001), which we aredeveloping at NASA / Ames Research Center.1 The components of a Brahms model are fairly easy to understand:

• People (Agents & Groups, e.g., biologists, the Phase 2 crew, the Capcom role)• Geography (the building and its layout)• Objects (e.g., cameras, tables, suits, documents)• Activities (e.g., reading email, EVA prep, watching movie, downloading & sharing digital photos, debriefing,

sleeping, waiting for help to remove suit)

Why do we want to build such a model? Wouldn’t it be sufficient to write an ethnographic report? Most importantly,model building is a tool for developing better social-psychological theories of human behavior. Through building theFMARS model, we have come to better understand the nature of joint activities (collaboration, e.g., filling the watertank) versus group activities (working together, but independently, e.g., using computers), the nature of dynamicinteractions (e.g., following someone) versus planned actions, and the different motives (e.g., having fun, physiologicalneeds) behind purposeful activity (Clancey, in preparation).

We also simulate life in the hab rather than just describing it because other aspects of the hab, especially the life supportsystems and controlling software, will be extensively formalized and simulated in computer programs as part of a designand test process. Without a complementary model of human behaviors, these system simulations will make assumptionsabout loads placed by human activities (e.g., the power required in the hab at different times). System simulations alsotend to use simple models of how people use an interface to command control adjustments or respond to control softwarerequests. Using Brahms, we can develop an integrated simulation of systems and human behavior.

Finally, during a Mars mission itself a simulation could be useful for testing and instruction of revised procedures. Forexample, we could revise a simulation to illustrate a new procedure, perhaps using new systems software, and thenupload the procedure, software, and integrated simulation to a Mars crew for them to investigate and interact with (i.e.,real people interacting with simulated systems and agents). This could provide confidence that the new design will

– 1 –

William J. Clancey; Institute for Human and Machine Cognition; University of West Florida, [email protected]; On leave at NASA / Ames Research Center, Mountain View, CA.

work, as well as providing a valuable tool for eliciting the crew’s comments. With the inability to converse directly withthe crew (the support on Earth), we could even send simulated agents for the crew to interact with, agents who conveythe models and explanations of specialists back on Earth.

To summarize, the applications of a hab simulation include:

• Habitat design• Automation design and testing• Formalizing analog experimental protocols• Crew scheduling• Communication-coordination planning• Training (especially by interacting within a simulation)• Education – public outreach• Research on work and behavior modeling

Our immediate interest is to develop Brahms well enough so the various applications can be explored in researchprojects. For example, through NASA funding we have integrated the FMARS simulation with an existing simulationof an air recycling system and an artificial intelligence monitoring and control system (Malin et al. 2000). The FMARSsimulation will place loads on the recycling system, providing a contextual model of hab operations for testing the AIsoftware. Furthermore, the (simulated) crew will interact with the AI software, for example, getting information aboutresource capacity (e.g., oxygen reserves) needed for planning daily work. Applying the methods of instructionalsystems (e.g., Clancey & Soloway 1990), we could develop programs that use a Brahms model to understand what thecrew is doing, so the programs could provide appropriate support.

MethodsHow do we build the FMARS model? There are two primary methods (Clancey 2001): Participant observation(learning by being a member of the crew) and photographic documentation (including time lapse). During my week inthe hab, I took regular notes about who did what, where, when, and why. Each day I added to this, refining with details,and finally developing hypotheses about why activities unfold in the manner I observed. In short, we need a theory of“what happens next.” What determines the next behavior of individuals and the group?

To organize my observations, I created a table in a document, with columns for the name of the activity, the locationwhere it occurred, the time, who participated, and comments. For regular activities, such as EVAs and meetings, I usedthe table to record when the activity began and ended. By the fourth or fifth day I was able to sort the table more or lesschronologically for a typical day and segment it into broader categories (e.g., breakfast, briefing / planning, EVA).Towards the end of the week, I began to refine some activities into subcategories (e.g., reasons for working at a laptop).Finally, after I left the hab, I realized the significance of activities and modes of behaving that I had not thought to writedown earlier (e.g., listening to music while working at the computer).

My other notes were organized in an outline of incidents and issues, as they emerged during my stay:

• Steps in an EVA• Troubleshooting incidents (e.g., electric generator, space suits)• Why staterooms are not used during the day• Traverse planning and navigation (e.g., avoiding mud)• Problematic spaces (e.g., the workstation area is cramped)• Non-issues (e.g., staterooms are quiet)• Learning from analog experiments; how to improve them

– 2 –

Simulating “Mars on Earth” – A Report from FMARS Phase 2

At various times I wrote down where everyone was in the hab and what they were doing. This provides a snapshot oflife in the hab (“snaplists”). In retrospect, I should have done this on a regular basis (e.g., once an hour), for it wouldbe a good way of verifying the simulation model. I had also intended to follow someone every day, to note theirbehaviors in some detail, but as a participant in the hab, where group activities dominated (mostly organized aroundEVAs), this proved impractical. Finally, after I began to understand why activities occurred when they did, I realized Ineeded statistical information about events (e.g., how often and when we received radio calls from base camp). Someof this information should have been logged by the crew (e.g., generator failures). Other information, such as externalcommunications, could have been logged by mission support.

It requires more than a week to realize all that one might study, especially if psychosocial factors are included. I believethat several weeks would be necessary to realize what categories are relevant; in general, multiple stays with differentcrew combinations are desirable for making generalizations and understanding crew-specific practices.

ResultsWhat are the results of my observations? I now have a table with about fifty activities, grouped according to broad “timesof the day.” Here is an initial description of these broad periods during a day in the life of FMARS 2001 Phase 2:

• 0700-0900 Breakfast• 0900-1030 Briefing / Planning• 1030-1500 EVA• 1500-1530 Eat and Clean up• 1530-1700 Briefing and planning• 1700-2000 Computers (email, photo download, software testing); data analysis in lab• 2000-2100 dinner and cleanup• 2100-2400 movies, refreshments (especially chocolate)• after midnight: sleep, reading and writing

This outline is a broad abstraction, an average of seven days, not a schedule we followed. Nevertheless, the patternscan be striking. For example, on three sequential days the EVA crew stepped into the airlock at 1105, 1106, and 1108.No procedure required that we do this, it was just an emergent product of our intentions, the constraints of getting intosuits and fixing radios, and our other habits (such as when we awoke, how long it takes to eat, and time to arrangepersonal gear). Absolute times will vary each day, but relative times, such as when a debriefing occurs after an EVA,are more regular (in this case, about 30 minutes). This chaining of group activities is a key part of the order of the day(which might be explained as part of individual, psychological processes).

What I have said so far should make clear why it’s not reasonable to expect a “human factors” report from the hab everyday, providing research results. Unlike the biologists and geologists, I do not collect isolated samples in plastic bags.My daily observations are mostly too mundane to mention (as the pattern itself hardly seems surprising). Also, it takesfour to five days until apparent habits are established, and then a few more days before details can be filled in (e.g., whatare people doing for so many hours at their computers?).

Time Lapse Video Example of EVA PlanningAn example analysis of a time lapse video reveals how I do my work and what can be learned. Based on an experimentin the initial year 2000 occupation of the hab, I placed my Hi-8 video camera in the far corner, in front of the right-moststateroom near the SE portal. I captured quarter-frame images (320 x 240 pixels) direct to disk every 3 seconds usinga PC Card and video-editing program. Experience in analyzing such time lapses since HMP-1999 showed thisfrequency to be useful and sufficient. I captured two entire days in this way. In retrospect, I might have left the timelapse running every day. Full analysis is tedious, but the time lapse is also useful for capturing broadly the behavior ofthe group during critical periods, as the following example illustrates.

– 3 –


Before the EVA of July 15, the group discussed where to go. I was not part of the EVA crew, so I sat to the side writing,but also observing. When the group all gathered around the commander’s laptop, I began paying more attention andtook photographs of the ensuing action. Similarly, the Discovery photographer picked up his video camera and beganfilming the action. The incident was immediately interesting because it illustrated a group planning activity, usingmultiple representations, coordinated with views through the portal, with people pointing and calling attention tofeatures throughout.

Fortunately, we have a time lapse recording of this activity, so we can see all movements, who is initiating changes, andwhen the changes occur (within three seconds). The group moves like a flock of birds during a 12 minute period,gathering at the laptop Landsat image (Figure 1), NW Portal (Figure 2), a projected map of crater, and an air photo ontable. Everyone participates. The commander tends to move in broad sweeps from one end of the floor to the other, tobe contrasted with pivoting around the central area of the floor or tagging along. One person appears to be interactingwith the commander most closely in these movements, suggesting a joint decision-making process. Another crewmember lags behind with his coffee, but always joins the group to share their view.

Strikingly, the activity is clearly over when the commander,the crew member who was speaking with him throughout,and two other crew members stand to form a square andlaugh. It looks like closure (Figure 3). The group thenobviously disperses to prepare for the EVA.

This example illustrates the value of having a time lapserecording at all times for the sake of capturing such groupactivities. The photographs also illustrate that theconventional manner of documenting such activity (noticethe Discovery Channel cameraman to the right of the groupin Figure 1) fails to capture the overall pattern of howpeople are gathering and moving as a group. The time lapseshows very well how one or two people reorganize theactivity by calling attention to different representations (thephotos and maps) and the views out the window. Thus, theuse of representations (including of course people’sutterances) is strongly contributing to individual attention,

– 4 –


Figure 1. Hab crew planning a traverse, gathered togetherto view a Landsat image of the von Braun Planitia on the

commander’s laptop computer.

Figure 3. Four members of the six-person crew, at the end ofthe decision-making process, now spaced around the room.

Figure 2. Hab crew planning a traverse, gathered togetherat the NW portal to view the von Braun Planitia directly.

such that we can talk about a group activity. Finally, the time lapse provides a means of quantifying the duration andphases of the decision-making activity. The end of the activity is particularly well marked (Figure 3).

How might this understanding of group planning be useful? Consider the value to mission support on Earth of such(time-delayed) video. If the group weren’t moving together, we might wonder whether there was a disagreement. Orperhaps the group had broken into subgroups to plan more quickly. Thus knowing what group planning looks like underdifferent conditions would be a useful clue to mission support about the crew’s attitudes. A theory of dialog as a spatialphenomena, not limited to a computer screen, would also be useful for designing robots that track human speech, gaze,and gestures to understand our intentions and communicate with us.2

Layout and use of spaceAn important part of the Brahms simulation of FMARS is a virtual reality depiction of the facility. The data gatheredincludes extensive photographs of all objects and areas, close-up photographs for color and texture rendering, and a scaledrawing of the hab (Figure 4). This drawing shows the layout at a particular time, with the precise arrangement oflaptops and chairs.

Figure 5 illustrates how Brahms simulations will appear on the computer screen using a browser. Although we call thisthe Brahms-VR system, the viewer is not immersed in the world, as in a virtual reality system. We refer to it as a 2 1/2ddepiction. The viewer could appear on-screen an “avatar,” a crew member in the simulation. In the prototypeimplementation, we use the Brahms-VR system to view a simulation after it completes. The target design involvesdynamic interaction, so one may view the simulation while it is running, and the simulation itself will draw upon physicsmodeling in the rendered world (e.g., to determine the path taken by an agent to avoid collision). There are manyfascinating problems to be solved here, including simulating agent postures, loudness of sounds (e.g., can someone onthe upper deck hear a conversation below?), sightlines, and joint actions (e.g., two people carrying an object).

– 5 –


Figure 4. Drawing of FMARS upper deck at 16:15 July 13, 2001.One chair is on the lower deck; accuracy of laptop locations and chairs etc. within 3”.

Of special interest is how use of hab facilities varies over time and with different activities (cf. Kantowitz & Sorkin1983). Photographs and other observations suggest that the layout of tables is perhaps the most important aspect ofspace design in the upper deck, aside from the staterooms and storage areas. The workstation area is the most obviousarea where design requires improvement. The built-in table is not deep enough (about 24 inches) and is too crampedfor six laptops plus a large server display (which hogs the most attractive area below the portal and blocks the view).The mess table provided extra space (Figure 6).

Figure 6 shows a group activity, in which people are gathered together. In contrast, Figure 7 shows the activity ofindividual work; people are apparently maximizing their separation.

Compare Figure 8, showing a different layout used by another FMARS crew, later in the field season.

Now it isn’t possible to sit around one table as a group (this crew went to base camp for dinner). More work area isprovided, relieving the elbow-to-elbow crowding of the curved workstation area along the wall. Consistent with thisconfiguration, the tables on the upper deck were used as a general workspace area during Phase 2. Besides eating here,people used the tables to: Play games, look at maps, clean cameras, prepare instruments for deployment, assemble and

– 6 –


Figure 5. Snapshot of virtual reality depiction of upper deck.

Figure 7. Individual work, maximizing spacing from each other. Figure 8. Alternative configuration in a different phase;separating the work area from the galley.

Figure 6. Using the table for a joint task (filling out a questionnaire)

test communications equipment, and analyze data (e.g., the magnification apparatus on the right table in Figure 8).Notice also how items are stored on the tables during the day, including cups, notebooks, samples, etc. Would samplesbe brought into the upper deck on Mars? Why aren’t equipment-related activities occurring downstairs? Issues ofspace, lighting, and room temperature need to be considered (the lower deck of FMARS was typically 5 degrees Ccooler). Perhaps also the group enjoys being together.

Activity Drivers: What determines what people do next?The most detailed aspect of the Brahms simulation is a description of each activity as a set of conditional steps oralternative methods. That is, the conditions – when an activity is performed – must be specified. Given the table ofactivities (outlined above), we see that group activities are the main driver of behaviors in the hab, fitting the chronologyof the day: Breakfast, Briefing, EVA, Debriefing, Dinner, and Movie. That is, during this phase in the hab, individualbehavior is constrained most strongly by coordinated group interactions. Furthermore, the daily EVA is the central,pivotal activity of the day, with meetings, preparations, and even meals occurring around it. This implies that thebackbone of the simulation will be behaviors individuals inherit (in the Brahms representation) from the “Hab Crew”group. Each behavior in Brahms is represented as a workframe, which is a situation-action rule. In general, the situation(conditional part) of the key workframes for Hab Crew activities will specify either the time of day (e.g., morningbriefing) and previously completed activities (e.g., the post-EVA briefing).

Interruptions are secondary driver of behavior, including: Radio calls (from base camp) or satellite phone calls (usuallypertaining to our communications systems), systems emergencies (toilet, comms), hab maintenance (refilling the waterreservoir, refilling the generators), and media interviews (conducted in the lower deck). Frequency information for theradio and phone calls might be determined from the time lapse. I did not have the time (or presence of mind) tosystematically gather information about the frequency and timing of when these activities occurred.

Individual activities, behaviors that are individually motivated and performed alone, fill the remainder of the day:

• science data processing (e.g., analyzing dosimeter data)• report filing (both individual reports and the daily crew report prepared by the commander)• email• digital picture processing (backup, sorting, sharing),• chores (cooking, emptying garbage, etc.)• personal hygiene• taking photos inside the hab (personal documentation)• recreational reading

In summary, the conditions on activities are the group’s practice, interruptions (reactive behavior), and individualpractice. Individual activities may be periodic (e.g., checking email), based on time (a crew or personal habit) or basedon remembering something you planned to do in the hab. Group practice is mostly chronological, but is also scheduledas required (e.g., cleaning the suits), chained (briefing follows an EVA), and reactive (e.g., handling emergencies suchas an electrical short in a backpack). Further analysis of this classification has led to better articulating the nature ofactivity model, as compared to activity theory and task analysis (Clancey in preparation).

Lessons Learned about Analog ResearchOf paramount importance, given the effort to build the hab, is determining what can be learned from an analog activitysuch as FMARS and how the activity should be managed and controlled as a scientific investigation. As incidents occur,such as problems with the generator and getting stuck in the mud during a traverse, one naturally realizes that thesimilarities and differences to Mars must be sorted out. Here is one breakdown:

• What is relevant to the Arctic only? e.g., refueling generators with gas• What might occur for different reasons on Mars? e.g., getting stuck in sand instead of mud

– 7 –


• What’s important that we might do better? e.g., interactions with mission support• What’s difficult on Mars but easy in Arctic? e.g., removing helmet to clean visor

In general, the operation of FMARS suggests a tension between authentic science (with mission support as required)and simulated operations (on the surface and at mission support). Taken to the extreme, the first point of view is thatFMARS is a research station to be used as a place for living and working in the Arctic, carrying out studies of scienceand robotics that are appropriate for Mars mission planning. The other point of view is that FMARS is first of all asimulated hab and crew occupations are simulated missions to Mars. In a simulation, there must be some clearly definedprocedures and a notion of “breaking the sim” (e.g., to clean a visor caked with mud during an EVA). This notion isnot relevant to the first idea, in which FMARS is just a habitat.

Is a compromise possible? Here is one suggestion: Analog habitats should be managed primarily for authentic science,as a real mission operation (with planning & training), and secondarily as a research vehicle that simulates Mars (e.g.,integration of hab, surface, and support operations). If the activities are not authentic, then the simulation has nogrounding. Alternatively, if the activities are authentic, then if the simulated constraints are limited but still valid, wewill still learn about scientific exploration relevant to Mars.

Authenticity in mission operations entails documenting communication and coordination protocols in advance, andtraining everyone in simulations prior to the field season. That is, living and working in the hab is viewed as being amission, not a sim. (It might be possible to do the sim on-site at the Mars Dessert Research Station, prior to the formaloccupation.)

Example of analog analysisAbstracting lessons from incidents is not easy. Often the literal events are irrelevant, but a broader moral lies in thetaken-for-granted context in which the event occurs. An incident during crew planning for an EVA illustrates my point.

The literal events are obvious to the observer: The hab crew is standing around the wardroom table, discussing how toset a GPS device for the planned von Braun Planitia EVA. Which GPS “system” should they use? The discussionconcerned the nature of a GPS measuring system, and revealed that there were two alternatives available on their GPSdevices (WGS84 [degree latitude and longitude] and UTM [metric distance]). One crew member claimed that UTMwas becoming standard; the people going on the EVA were more familiar with measurements in degree/minutes. Theydidn’t know how to use the GPS device to use or read UTM measurements.The lesson to be drawn is not that astronauts going to Mars should be trained on how to use their equipment or thatstandards should be adopted before the mission begins. Everyone already knows this. Surely a funded, actual missionwould have prepared the crew better. Rather, the less salient and important issue is that route planning was occurringjust before the EVA, not the evening before as I observed in HMP-1998 or as was deliberately scheduled during HMP-1999 to coordinate with a mission support team in Houston. If mission support personnel were involved in choosingroutes, then the crew wouldn’t be allowed to wait until just before departure to plan the EVA, this would have to be donethe previous evening. So why did this group develop a different practice? My observation is that we were too tiredfrom the day’s activities and too busy reporting what we had done to think about the next day. Thus, we may have areal issue here, which perhaps we thought we had understood in 1999. (Also, the 1999 after-dinner communication withHouston focused more on reporting than planning.)

The example illustrates how a simple incident had to be interpreted in the context of previous field seasons, withbackground knowledge about past NASA practices and expectations. From this we see that FMARS provides a researchopportunity for communications research, which can be exploited by enlisting more collaboration and establishing moreformal protocols for hab activities (e.g., working more rigorously according to a schedule that is coordinated with Earthoperations). Do we have the funds and committed external organizations (e.g., NASA, the Mars Society) to provide arealistic mission support role? Or should communications research using FMARS be focused more on interactionsbetween the EVA crew and the hab?

– 8 –


The GPS example also illustrates that superficial reports about FMARS operations are unlikely to give the viewer anunderstanding of what we are actually learning or could learn from future analog experiments. Such analysis isespecially the province of participant observers and modelers who study the scientists and operations in the analogsetting, applying the methods and perspectives like those I present in this report.

FMARS Research OpportunitiesWhat scientific research can be done at FMARS? Researchers may want to consider this list when making proposalsfor participating in hab activities:

Communication Protocols• Enforce and document communications between EVA crew and mission support. Investigate especially exchange of

contextual information and instructions for using equipment.• Contrast: Commander serves as communications hub with world’s experts / advisors vs. specialists in the crew

individually communicate with their own peers and private contacts• Improve communications between the EVA crew and hab support using radio and video to provide a running commentary

Computer Infrastructure• Integrate computers used for data gathering and analysis with the hab’s communications and computing system• Facilitate and study data sharing among the crew (e.g., exchanging files using compact flash cards vs. a shared network)• Develop computer records that crews leave behind for subsequent crews: Photographs, articles, history of activities,

maps (should mission support provide or supplement this repository?)

Laboratory and Data Analysis• Determine the adequacy of laboratory equipment in the hab for data collection and analysis (e.g., rock slicing,

microscope with camera)• Work collaboratively with experts on “Earth” for data collection planning, analysis, and interpretation.• Determine laboratory space required and how to prevent intrusion from other activities

Living and Working Priorities in the HabAs a rough cut, one can order priorities for the crew’s attention, based on basic needs and their interactions:

• Electricity, Toilet (electric), Water (pumped from outside hab), Food• Private and quiet areas, especially dry and well-ventilated staterooms• Unscheduled time for sleep and individual activities• Work areas with adjacent space for personal items (e.g., notes, drinks)• Personal storage areas (e.g., for cameras to be ready at hand)• Dry and warm EVA clothing (suits)• Cleanliness (showers, hot water)• Entertainment (e.g., DVD movies)

Possibly the only item in the list of living and working priorities that might differ from previous studies of expeditions(e.g., Stuster 1996) is the relative priority for unscheduled time. Because of good weather opportunities, interest intrying the suits, presence of the press, and shortened phase duration it was desirable to have a significant EVA each day.Preparation and reporting filled most of the remaining time, so the crew was far from being bored or feeling confined.A pre- and post-occupation survey related to this list would be useful.

Using Brahms, we could formalize different schedules, layouts, and resource decisions (e.g., use of water). Design ofspace habitats and missions will likely involve many tradeoffs and compromises, which a comprehensive simulationshould enable us to describe and evaluate.

– 9 –


AcknowledgmentsI am grateful to the members of the FMARS Phase 2 crew for participating in this research: Steve Braham, CharlesCockell, Vladimir Pletser, Katy Quinn, and Robert Zubrin. Conversations with Pascal Lee (Principal Investigator of theHaughton-Mars Project), Maarten Sierhuis, Mike Shafto, and members of the Brahms team have been especiallyvaluable. For more information about Brahms see http://www.agentisolutions.com and papers athttp://WJClancey.home.att.net. Funding for this research has been provided by the NASA’s Intelligent SystemsProgram, Space Human Factors Engineering, and University of West Florida. The virtual world representation of thehab has been developed by Bruce Damer and his associates at Digital Space, Inc. under NASA-STTR funding. Seewww.digitalspace.com for information about the Adobe Atmosphere implementation.

References1. Clancey, W. J., Sachs, P., Sierhuis, M., and van Hoof, R. 1998. Brahms: Simulating practice for work systems design. International Journal

of Human-Computer Studies, 49: 831-865.2. Clancey, W. J. 2001b. Field science ethnography: Methods for systematic observation on an Arctic expedition. Field Methods, 13(3), 223-243,

August.3. Clancey, W. J. (in preparation). Simulating activities: Relating motives, deliberation, and attentive coordination. Cognitive Systems Research,

special issue on situated cognition.4. Clancey, W. J. and Soloway, E. (eds.) 1990. Artificial Intelligence and learning environments. Cambridge, MA: The MIT Press.5. Kantowitz, B. H. and Sorkin, R. D. 1983. Human factors: Understanding people-system relationships. New York: John Wiley.6. Malin, J. T., Kowing, J., Schreckenghost, D., Bonasso, P., Nieten, J., Graham, J. S., Fleming, L., MacMahon, M., and Thronesbery, C. 2000.

Multi-agent Diagnosis and Control of an Air Revitalization System for Life Support in Space. Proceedings of 2000 IEEE AerospaceConference.

7. Sierhuis, M. 2001. Modeling and simulating work practice. Ph.D. thesis, Social Science and Informatics (SWI), University of Amsterdam,SIKS Dissertation Series No. 2001-10, Amsterdam, The Netherlands, ISBN 90-6464-849-2.

8. Stuster, J. 1996. Bold endeavors: Lessons from polar and space exploration. Annapolis: Naval Institute Press.

– 10 –


Send A (Software) Agent On A Mars Mission?

Ned Chapin[1999]

A software agent is like a skilled surrogate to whom a person has delegated a measure of authority, but the agent takesthe form of computer software. The three main kinds of software agents come in five performance levels, and all differfrom traditional computer applications. The typical software agent acts like an errand runner, or like a messenger set of“ears and eyes,” and typically provides a way of automating tasks that people find to be mundane dull and repetitive.Six important determinants of a software agent’s usefulness in Mars missions are the agent’s capabilities, the scope ofthe accessible data, the natural barriers present, the intentional barriers in place, the skills of the agent’s principal, andthe facilities and resources of the mission’s supporting infrastructure. A description of seven examples of possible rolesof agents on Mars missions highlights some aspects of the potential contribution of software agents. This leads to areview of six major reasons why Mars missions will want to use agents, and four major reasons why Mars missions willnot want to use agents. The conclusion is that the pro reasons will outweigh the con reasons, in order to enhance thevalue that human beings can contribute in Mars missions. But the con reasons are sufficiently strong to lead tolimitations in the use of software agents on Mars missions.

What is a Software Agent?A software agent is a specialized computer program that operates in a communications-rich environment.1 It utilizesthat environment’s directory and switching facilities to pick message destinations and to change the routing of messages.It utilizes search functions to find alternative destinations and data. It uses data formatting and storage functions togenerate messages and to provide a report on what it accomplished. The initial primary use of software agents has beenin gathering data accessible via the World Wide Web. Software agents have been likened to errand-runners.2 Theirowner-users – i.e., principals – tell them to go do something or to get some data. Once the principal tells the agent tostart work, the agent attempts to perform the task the principal requested including sending and receiving messageswithout further guidance or intervention from or interaction with the principal. The agent is on its own in getting thetask done. But the agent always reports back to its principal, with data indicating the extent to which the agent wassuccessful in getting the assigned task completed that the principal had specified.

Effectively, this makes the agent a surrogate of the principal. Because the principal is the person who assigns the taskto the agent, activates the agent, does not intervene during performance, and receives a report from the agent, theprincipal effectively makes a specific delegation of authority to the agent. Hence, the principal tacitly assumesresponsibility for what the agent does or fails to do. To minimize this responsibility, a popular role for agents has beento serve as additional sets of “eyes and ears” for the principal. The tasksassigned to such agents are usually to use messages to gather and reportdata. An example on the World Wide Web of such an agent for whichnearly anyone can act as a principal, is the Ask Jeeves agent.3

Three kinds of agents are local or mobile, transient or persistent, andaction or intelligent. Combinations are possible and common, a situationdiagrammed in Figure 1. A local agent is resident on and works from itsprincipal’s computer. A mobile agent communicates itself to one ormore different computers and does part of its assigned task from thosecomputers as well as from its principal’s computer. Local agentscurrently are more common than mobile agents. A transient agent iscreated for and exists only until a task is done, when it then expires – i.e.,it can only be used once, and if wanted again, must be recreated orspecifically reinitiated. A persistent agent can be used over and over

– 1 –

Ned Chapin; InfoSci Inc., Box 7117, Menlo Park CA 94026-7117, USA; Email: [email protected]

Figure 1. The three kinds of agents eachhave two prominent forms.

again, and survives power downs of the principal’s computer. Most agents are made to be persistent because they havethe potential for continuing usefulness. An action agent delivers data to a receiver other than its principal, usually forthe purpose of directing an action, and informs its principal of the status of the data delivery, such as “antenna selectorset to low gain, 1999 Aug. 15, 16:37:04.” An intelligent or decision-making agent applies criteria to filter data and mayprocess data to fit its principal’s specification. Both intelligent and action agents are common. Software agents havefive levels of performance. These actually are just regions along an irregular line of increasing performance capabilities.Agents at the three higher levels typically have the ability to utilize the results from agents they themselves generate –i.e., they may launch and use cascades of subordinate agents. The list below of performance levels goes from low tohigh:

• Find-deliver-report. These agents find a communication path, use it to send data as specified by their principals, andreport back to their principals about their successes or failures. Interfacing with digital-to-analog and analog-to-digital equipment may be involved. An example is the action agent noted above that reported “antenna selector setto low gain, 1999 Aug. 15, 16:37:04.”

• Find-extract-report. These agents find one or several communication paths, use it or them to request, acquire, andcommunicate a copy of some data, and report these data to their principals. An example is an agent that finds outand reports on the processing status of a proposal for an increase in mission funding.

• Find-analyze-deliver-report. These agents find one or several communication paths, use it or them to request,acquire, copy, and then analyze data, and afterward deliver some data selectively before reporting back to theirprincipals. An example is an agent that fills out and submits a simple business form for its principal, such as aconference hotel reservation request.

• Find-extract-filter-report. These agents find communication paths, use them to request, acquire, and communicatecopies of some data that the agents then process with respect to some specified criteria, reporting the resulting datato their principals. Some include learning capabilities. An example is an agent that locates the specific location onMars that at this particular time has largest dust devil moving more toward the equator than toward the pole.

• Find-extract-filter-integrate-report. These agents add the additional process of attempting to integrate data fromdiverse sources that may require iterative find-extract-filter performance capability and may require interacting withother software or other agents or both, before they report to their principals. These agents are still in the early stagesof their maturation, and some include learning capabilities.

Software agents are a kind of computer application, and share many characteristics in common with computerapplications generally. For example, they consist of computer software, they may be done in any computerprogramming language (such as Java4) and use any technology (such as object-orientation), they may access files anddatabases, they may interface or interact with other computer applications, and they may cause other software to run orcease running, including other agents. However, software agents are different from traditional computer applications ina number of ways. All of the following five differences must usually be present for the computer application to be asoftware agent:

• Communications-rich environment. Computer applications can be developed to run in any operating environment.Agents are specialized computer applications that require a computer communications-rich infrastructure. Thatinfrastructure must provide for relaying and switching messages over a network of computer-implemented nodeswhere the nodes and the message conform to accepted protocols. The infrastructure must provide some directoryservices, and some store and forward services. A strong communications infrastructure has been identified in priorwork as a desirable feature for most Mars missions.5 An intranet is an example.

– 2 –


• Limited functionality. Computer applications can be developed to have from scant to enormous amounts offunctionality. Agents are specialized computer applications that have limited functionality, like that granted typicallyto errand runner and “go for” personnel. Two functions always present are message handling, and reporting to theprincipal. Other functions present depend upon the agent’s level of performance, but the extent and variety of suchother functions are usually low. An agent may operate on inventory data or human resources data, but an agent ismuch less comprehensive in functionality than an inventory system or a human resources system.

• Run at pleasure. Computer applications can be developed to run anywhere from continuously to periodically to irregularlyas needed. Agents are specialized computer applications that either run periodically or on their principals’ demands. Thatis, the principal can set a specific schedule for when the agent is to run, or can on a per instance basis select when a agentis to run. A software agent very rarely runs endlessly, but may run continuously for a fixed time duration.

• No in-process guidance. Computer applications can be developed to accept directive input data to any degree and atany time to provide guidance during a run. Agents are specialized computer applications that accept guidancenormally only at the initiation of a run. Once initiated, agents normally run self-directedly without seeking orreceiving from their principals additional guidance or directions during the run.

• Routine task focus. Computer applications can be developed to have from a very narrow to a very broad focus, andcover tasks that may be from very simple to extremely complex. Agents are specialized computer applications thatusually focus on the tasks that people find to be necessary but routine, dull, mundane, or boring – sort of theequivalent of tying one’s shoes. Agents act like extra sets of eyes or ears or hands to relieve people from routinetasks yet still give them the benefit of having the tasks done to their tastes. This can free people to spend more oftheir time on what people are uniquely good at doing – handling the unexpected and the non-routine and thestimulating tasks. Some varieties of traditional computer applications may appear to be agents, but really are not.One example is a calendaring program. While it serves usually just a single user, it does not require acommunication-rich infrastructure. However, when a communications-rich infrastructure is present, some advancedcalendaring programs use agents to coordinate different people’s schedules, as in setting up a date and time for ameeting. A second example is a computer virus. The releaser of the virus does not receive a report from the virusprogram of the program’s infestations. A third example is the program that was used to control the Mars Sojourner.Brian Cooper sat at a 3-D display at JPL and interactively provided guidance during a run. A fourth example is afirewall. While it gathers data in a communication-rich environment, analyzes, filters, and reports (securely) to aspecific person, it runs endlessly. A fifth example is a disk defragmenter program for improving hard diskperformance on a computer. Even though it runs at its user’s pleasure, such a utility program does not require acommunication-rich infrastructure in order to run, and it reports nothing beyond a completion notice back to its user.

Production and Improvement of AgentsThe production of agents for Mars missions will at least initially follow the common practices. Agents may bedeveloped to act as solo performers, or as collaborators, or as performers in a hierarchy of functionality implementedwith a mix of agents and traditional application software. Most personnel assigned to produce agents are usually eitheroutside contractors or from an organization’s Information Technology (IT) or Information Systems (IS) unit. Morerarely, a developer may be an individual who sees an opportunity and has sufficient expertise. The correction orimprovement (“maintenance”) of agents usually gets done by the developer or by personnel from same organization thatdid the initial production (“development”) of the agents. When the original source does not supply the requestedmaintenance within a reasonable time and cost, then the personnel actually using the agents either do the maintenancethemselves or seek an alternative source for it. Unmet maintenance on agents puts the same kind of drag onorganizational performance that does unmet maintenance on software generally.6 The four most common ways ofproducing and improving agents are these:

• The traditional life cycles for development (“SDLC”) and for maintenance (“SMLC”) are followed using theorganization’s traditional assortment of processes, methods, techniques, and tools. Costs tend to be substantial and

– 3 –


depend on the level of performance wanted. Because specific software agents commonly help the work of oneperson or a small group of persons, the total return or value to the organization comes out usually low to develop andmaintain agents. Hence, getting the development and maintenance done at all by an organization’s IT or IS unit canbecome a hurdle when using a traditional approach. This tends to encourage a do-it-yourself approach amongpotential principals who have sufficient expertise.

• Software generators sometimes provide an alternative for getting agent development and maintenance done. Thesetypically provide a selection of templates that the developer customizes before executing to produce the agent.Instead of maintaining the agent, the principal has a new agent generated and uses it instead of the agent previouslyused. The organization’s IT or IS unit may use software generators to save time and money in meeting principals’requests for new or improved agents.

• Agent generators are specialized software generators specifically for producing agents. The developer specifies tothe generator the interface wanted between the agent and the principal, and what the agent is to do (an example isLiveAgent7). The resulting agent typically requires that the principal have on the local computer a special softwareenvironment to support the generated agent. Instead of maintaining the agent, the principal usually has a new agentgenerated and uses it instead of the agent previously used.

• Learning agents are general purpose agents that are trained by the principal using them, somewhat like the processof training speech recognition software to translate spoken words, given a user’s accent and pronunciation. Thismakes the development time short because the general purpose agent already exists, awaiting training. The trainingprocess converts the principal’s attempts to use the agent into frequent series of agent maintenance episodes, for theprincipal effectively is the maintenance performer. The gain for the principal is personal control over the agent’sperformance. Learning agents are only now starting to be introduced.

Determinants of Mars Mission UsefulnessAgent Capability:The capability of a software agent depends mostly on two factors: 1 – the technical expertise of the people who developand maintain the agent, and 2 – the quality of the communication among the principal and the developers andmaintainers of the agent. Both are critical, and typically keep changing as time passes.

Scope of Accessible Data:The data accessible to the agent come from five main sources:

• New data acquisition activities,• Existing mission files,• Existing mission databases,• Private data uncovered as a result of searching, and• Publicly available data, as from libraries, the internet, government agencies, etc.

The data acquisition process, such as of the heat loss rate from the regolith at a location on Mars, may yield data indigital form directly, or may need analog to digital conversion. In either case, the need for data reduction is common.In some cases the data are so voluminous, such as data for mapping from synthetic aperture radar work, that the datareduction requires a full-scale computer application. In other cases, the data amounts are modest and may be easilyhandled by a software agent, such as of the heat loss rate noted above.

Natural Barriers:The natural barriers mostly reduce data accessibility for the agent. Human forgetfulness, time zone differences, sun spotinterference with data transmission, loss of signal, personnel skill levels, hardware failures, bad weather (such ashurricanes, ice storms, tornadoes, etc.), earthquakes, cultural differences (such as holy days and holidays), personal

– 4 –


health, and human conflicts can all be natural barriers adversely affecting agent performance. Less common naturalbarriers typically come from limitations in scientific knowledge or engineering accomplishment, such as remotelyassessing the extent of an aquifer on Mars.

Intentional Barriers:Intellectual property rights in data and professional ethics can be significant intentional barriers affecting dataaccessibility. Firewalls, password protection, budget limitations, language and coding conventions, and data encryptionare barriers that can degrade or block agent performance.

Skills of Principals:The skills of the principals are partly in the use of the agent, and partly in the design or specification of the agent. Thelatter reflects the vision and desires of the principal – i.e., what the principal wants the agent to be able to do. Thisdepends greatly for Mars missions on the principal’s mission knowledge and role, and to a lesser extent on theprincipal’s ability to see and understand the broader picture and context in which the principal and the mission operate.Skill in using the agent can nearly always be improved by experience and experiment, or training. Most of the time,most principals use less than a quarter of the capabilities of their software agents.

Infrastructure Facilities and Resources:The extensiveness and richness of the computer and communications infrastructure significantly affect what agents cando in three ways:

• Number and variety of data sources accessible,• Remote capability invokable by the agent to support its performance, and• Time required for the agent to do its work.

When the agent requires an infrastructure facility or resource to accomplish part of its work, the agent may either sufferimpaired performance or may attempt to seek elsewhere for the facility or resource. Either places a burden on theinfrastructure of increased communication load and increased processing load, and hence at the best, longer time for theagent to accomplish its work.

Examples of Possible Mars Mission RolesGet Surface Wind Velocity and Direction:Consider the possibility that a manned or robotic base on Mars had twelve robotic meteorology data gathering sitesplaced at significant points within a twenty kilometer radius of the base including a site at the base, transmitting gathereddata four times a sol to the base computer. A meteorologist might want to know at any time what was the surface windvelocity and direction at some specific site or set of sites at a specific time subsequent to the most recent transmission,such as now. A mobile persistent intelligent find-extract-report software agent could meet this need.

Scan Data on Ultraviolet Radiation Consider that as part of a research project on the effects of the ultraviolet flux on thesurface of Mars, a large database has been accumulated, a database that grows with each passing sol. The project’sprincipal investigator might want to sniff the database for hints of trends that might point to research hypotheses worthtesting. A local transient intelligent find-extract-report software agent could meet this need if the agent could bemodified easily and quickly.

Direct Change of Action Alternative:Consider a robotic hydrological project on Mars, with a computer-controlled drill, searching for underground water. Thespent special drilling mud is continuously analyzed on an automated basis, and the analyses reported on a regular basisto the distant headquarters for human review. To meet non-routine situations, the headquarters staff could use a smallcollection of software agents. For example, a mobile transient action find-deliver-report software agent could direct,when the drill string has been withdrawn, what sensor probe to send down the hole, how far down, and at what levels

– 5 –


to take readings. Such use of agents can simplify the application software that controls the drilling process, and give abetter degree of supervision to the human personnel.

Locate a Needed Skill:Consider a situation where the project team members on a Mars mission encounter an unexpected situation, where theyrealize that even collectively they lack among themselves the skill, knowledge and experience to devise and carry out anappropriate action response. They need to locate what they lack. For this purpose, a mobile transient intelligent find-extract-filter-report software agent could search broadly for personnel who might be able and available to satisfy the need.

Establish Communication With a Resource:Consider a situation where new geological research in the Canadian Arctic and Greenland has developed findings thatmay be useful in interpreting the evidence of the geological past of Mars. However, the formal report lacks details thatmay be helpful for an application to the Mars situation, and the research was not done by or for any Mars mission. Amobile transient action find-analyze-deliver-report software agent could seek out acceptable communication linksbetween the Mars team and the geological researchers, given their respective situations and the general character of thelikely data to be transmitted in each direction.

Find a Component to Fit a Specification:Consider the situation where the project team on a Mars mission realizes that the team needs a specific component tofit a specification. But the available inventory of components (parts) is long, the stock numbers are non-mnemonic, andthe nomenclatures are abstruse. How can the component be found? A persistent mobile intelligent find-extract-filter-integrate-report software agent could sleuth out the component and report its last known location, or if it be unavailable,what are the suggested substitutes.

Place an Order for a Component:Consider the situation where a needed component is unavailable, and the easy substitutes are not up to the demands ofthe project team on a Mars mission. The question is then “make or buy or jerry-rig,” and whether any are viable options.The more specific the team members can be in their requisition, the better service they can receive from their purchasingor fabrication support personnel. A persistent mobile intelligent find-extract-filter-integrate-report software agent couldacquire and refine the data needed for a useful requisition to result in either a placed order, or fabrication directions, ora work-around. In practice in such situations, the agent gets used repeatedly and may be modified as the refinementprocess done with the data reported homes in on the suitable alternatives.

Pros of Using Software Agents on Mars MissionsThe common reasons for proposing to use software agents on Mars missions all relate to improving the effectivenessand efficiency of the mission personnel. Six major “pro” items are these:

• Save personnel and calendar time. An appropriately selected and deployed agent allows the principal to getacceptable quality work done faster.

• Cut personnel effort. By using an agent, a principal can get some kinds of work done more easily with less botherand less burden on other personnel.

• Reduce data overload. The principal can have an agent use available computer power to analyze and filter databefore reporting them.8

• Raise level of personnel accomplishment. Within available time and resources, the principal can use agents likepersonal extensions to improve both the quality and the quantity of work done.

• Improve work consistency. Between modifications, an agent acts the same way each time it runs, assuming thedirections it receives and the context in which it operates are unchanged. Agents can be shared and used by multipleprincipals to add more stability to the performance of the involved personnel.

• Facilitate changes to meet changing needs. Usually when the team members of a Mars mission realize that they havenew needs or that their needs have changed, they have the option to modify their software agents to address the new

– 6 –


set of needs. However, sometimes meeting some new needs can be best done by developing and using either newor replacement agents.

Cons of Using Software Agents on Mars MissionsThe usual main reasons for not using software agents on Mars missions focus on resource utilization and management.Five of the most common reasons are:

• Agent performance depends on infrastructure. The natural and imposed barriers can limit the performance of agentsto the point of making them nearly useless. The most common difficulty is that the infrastructure does not adequatelysupport the agents. Much of the infrastructure used by some mobile agents may be beyond the control orresponsibility of the Mars mission.

• Agents burden the mission resources. The mission personnel who are the principals for agents take time to send outtheir agents and to work with the data they return. Since only the simplest persistent local action agents are havehigh complete success rates, and since the partial failure rate rises as agents become more complex and mobile,principals can often waste time and effort in trying to get adequate performance from their agents. When a manager’ssubordinates use software agents, the manager’s supervision role becomes more difficult to do. Agents take upcomputer storage space not only on the computer most-used by their principals but also as the agents are used, onthe mission’s other computers. Agents add a bursty and largely random demand on the available bandwidth used formission communications. Specialized mission support personnel are needed for agent development, for otherwisedoing agent development adds to the work of either principals or agent vendors or contractors. Agent maintenancemakes a similar but greater demand on mission resources and management.

• Agent usage reduces privacy and security. While mobile agents’ potential invasions of the security of data and theprivacy of personnel outside of the Mars mission may be of lesser concern to the mission, local and mobile agents’potential invasions are of more noteworthy concern as regards the security of personal and mission data and theprivacy of mission personnel. The typical agent seeks data wherever it can obtain access that might be relevant. Thatcould be on a computer used by a principal’s co-worker or manager, or at a competitor’s site.

• Agent existence invites “anti-agents” and “evil” agents. To attempt to improve privacy and security protection,computer users sometimes feel impelled to take counter action to try to thwart agents that may try to access data ontheir computers. These typically take the form of intentional barriers installed both at shared and unshared computersites. An example is a firewall. Installing, using, and maintaining such protective measures add to the burden onMars mission resources. Protection against “evil” agents is difficult. An example of an evil agent is the softwarecreated and used by hackers to snoop the contents of computers, files or databases for which they have no authorizedaccess. For instance, consider the software used to try to steal a copy of the credit card numbers and names ofcustomers of an e-commerce organization, or to copy classified data from a military headquarters.

DiscussionThe possible use of software agents on Mars missions has technical, managerial, and ethical aspects. These interact inways that depend upon goals, objectives, contexts, and circumstances. The technical aspects focus on the computercommunications-rich environment. Without it, software agents are limited in scope to accessing the data stored in justone computer, the computer in which the agent itself runs as a minor occasional application. Computer communication-rich environments typically require computers in server roles and connected communications gear in order to operate –and that is in addition to whatever computers and associated local networking gear are used to connect the principals’computers. While the hardware costs continue to fall and hardware capabilities continue to rise, personnel costs tooperate and maintain the computer communications-rich environment drift ever higher. Some software can help holddown the personnel and hardware costs, but supporting a rich computer and communications infrastructure is a(necessary?) burden on a Mars mission. The managerial aspects arise partly from the technical aspects just noted, andpartly from other factors. A Mars mission is not an independent entity, but relies on many other entities, some of whichmay want to send software agents to access mission data, and some of which mission personnel may need to access (asvia software agents) as part of carrying out their roles effectively.9 In addition, both the mission environment and thesurrounding context are technologically heterogeneous and evolving, with a mix of old and new technologies. Personnel

– 7 –


skills, knowledge and experience also keep changing. None of these changes typically are in synch with changes in theever-changing demands upon the mission. Software agent capabilities add to potential flexibility, but also add to cost.The cost benefit balance is not static, and is complicated by difficult to quantify personnel and personal considerations.The ethical aspects arise mostly from trying to find an acceptable balance between good professional science,engineering, and personal respect on the one hand, and the demands of the mission on the other. For example, someonesomewhere (such as a privately funded doctoral candidate at a university) having no affiliation with the Mars mission,may be gathering data on a topic relevant to the mission, but not yet have the data fully analyzed and ready forpresentation or use. A member of the mission’s personnel acting as a principal might send out a software agent to locatedata on the topic, and the agent might find and report either a copy of the data or of the analysis results thus far. Theprincipal then does or completes sufficient analysis to make data immediately usable to try to meet a pressing criticalcurrent mission need. Later, the principal might or might not send the source of the located data a “thank you” email.Should the data have been accessed? Should notice have been given? Should the data have been used? Shouldrecognition have been given? Should payment have been made? Should compensation to the source have been made forthe consequences of the loss of publishable results? Should a liability claim have been pressed if the mission result didnot turn out as hoped?

ConclusionsA review of the pros and the cons points to an answer for the question in the title of this paper: “Send a (software) agenton a Mars mission?” The rising costs of personnel and the falling costs of hardware will dominate, given the need tohave a strong communications capability in place on Mars missions. To help personnel be and stay productive, Marsmissions will send software agents for doing routine local repetitive tasks that can be satisfied by a find-deliver-reportor find-extract-report level of performance. Beyond that, moderation in usage will be expected, at least initially, byasking mission personnel to respect limitations on the use of transient and mobile agents, and on all agents when higherlevels of performance are sought.

References1. J. Bradshaw (ed.), Software Agents, MIT Press, Cambridge MA, 1997.2. M. N. Huhns and M. P. Singh (eds.), Readings in Agents, Morgan Kaufman, San Francisco CA, 1998.3. Ask Jeeves, Inc., URL: http://www.askjeeves.com/4. D. Wong, N. Paciorek and D. Moore, “Java-based Mobile Agents,” Communications of the ACM, Vol. 42, No. 3, March 1999, pp. 92-102.5. N. Chapin, “Adaptable Software Needed for Mars Missions (AAS 93-866),” Case for Mars V (Science and Technology Volume 97), Univelt,

Inc., San Diego CA, pp. 91-105.6. N. Chapin, “Software Maintenance Characteristics and Effective Management,” Journal of Software Maintenance, Vol. 5, No. 2, March-April,

1993, pp. 91-100.7. B. Krulwich, LiveAgent, AgentSoft Ltd., Jerusalem, Israel, 1999.8. P. Maes, “Agents that Reduce Work and Information Overload,” Communications of the ACM, Vol. 37, No. 7, July 1994, pp. 31-40.9. A. K. Jain, M. Aparicio and M. P. Singh, “Agents for Process Coherence in Virtual Enterprises,” Communications of the ACM, Vol. 42, No.

3, March 1999, pp. 62-69.

– 8 –


Spacecraft Systems Design of a Manned Mars Vehicle SystemA Fourth Year Student Team Project Using the Internet

W. Brimley, Ph.D., P. Eng.[2000]

ABSTRACTSeven student teams at four Ontario universities (Queen’s, Royal Military College, Ryerson and York) were challengedto perform the preliminary system design for a manned spacecraft capable of leaving Earth and traveling to Mars. Thecrew is to land on the Martian surface, explore and then return to Earth. This manned mission to Mars uses the optimumcombination of the “Mars Direct” approach proposed by Robert Zubrin, and the NASA Reference Mission. The mannedmission would use departure from the International Space Station (ISS), with a direct descent to Mars using aerobrakingand parachutes, or a transfer vehicle may be left in orbit around Mars for the Earth return.

The complete spacecraft system to be designed, including its Ground Control Segment, is named the MMVS (MannedMars Vehicle System). Other components such as the propellant manufacturing plant and the nuclear power plant wereassumed to be available. However, complete mission planning including the precursor unmanned mission to place thesecomponents on Mars was performed.

The results from the teams are summarized and compared. Student representatives will discuss their design and issuesthey found. This presentation focuses on the achievements of students by demonstrating results from the team web siteswhere the final reports are mounted. Benefits to our students such as participation in events such as this Mars SocietyConference are noted. Many former staff and student alumni are now employed in the space industry, or are enrolledin post-graduate programs in universities including the International Space University.

The Interactive Learning Connection – University Space Network (ILC-USN) is a consortium of North AmericanUniversities, Centres of Excellence, and industry that has successfully established an Internet based course in“Spacecraft Systems Design.” Since the fall of 1995, 255 undergraduate and 13 graduate students have completed thiscourse at universities in the United States, Canada and Mexico.

1.0 Project Introduction – Manned Mars Vehicle System (MMVS)Student Teams were challenged to design a manned spacecraft capable of leaving Earth and traveling to Mars. The crewwill land on the Martian surface, explore and then return to Earth. The project will be a manned mission to Mars usingthe optimum combination of the “Mars Direct” approach proposed by Robert Zubrin, and the NASA Reference Mission.

Royal Military College (RMC) recommended a “Modified Mars Mission” That would use departure from theInternational Space Station (ISS), with a direct descent to Mars using aerobraking and parachutes. The return trip wouldbe to Low Earth Orbit (LEO).

The student Teams are required to calculate departure from Earth orbit (i.e., the spacecraft velocities and delta V’srequired) to travel to Mars and land on its surface. Then, after a stay on Mars, to calculate the return to Earth orbit. Wecan assume the (MMVS) spacecraft will be assembled in low Earth orbit at the new International Space Station. Sizingof the vehicle will be driven by the velocities and corresponding fuel mass calculations for a given payload (e.g., crewcompartment, ascent vehicle, etc.).

1.1 Mission StatementThe mission is to send a manned spacecraft to land on the planet Mars and after the crew explores Mars to return thecrew safely to Earth.

– 1 –

W. Brimley, Ph.D., P. Eng.; Operations Manager, Interactive Learning Connection – University Space Network,School of Aerospace Engineering, Ryerson Polytechnic University

The term project is to perform the preliminary system design of the manned spacecraft systems and components capableof this mission. This complete spacecraft system to be designed, including its Ground Control Segment, is namedMMVS (Manned Mars Vehicle System). Other components such as the propellant manufacturing plant and the nuclearpower plant will be assumed to be available. However, complete mission planning including the precursor unmannedmission is necessary.

1.2 Background1.2.1 MARS Direct Plan (Zubrin)Note: the following is a combination of Zubrin’s proposals.

1. Begins with the launch of an unmanned Earth Return Vehicle (ERV) that will land on Mars and manufacturepropellant.

2. Two years later another ERV and a Manned Spacecraft (MMVS) leave Earth for Mars. The MMVS lander landsnext to the previous ERV and manufactured propellant. The second ERV may also land in close proximity toprovide a backup return vehicle (or land within a 300 km range from the initial ERV).

3. The crew leaves Mars after one and one-half years, using the first ERV. A second manned mission and third ERVmay land before they depart (more backup).

4. The landings continue, leaving a string of landing sites (base camps) across the Martian surface.

1.2.2 NASA Reference Mission1. An unmanned ERV is placed in orbit around Mars. It is fully fueled and capable of remaining on orbit for over four years.2. An unmanned cargo lander is launched and landed on Mars. It contains an unfueled ascent vehicle, propellant

production plant, nuclear power plant, and Habitat.3. A manned lander is launched and lands in close proximity to the cargo lander. The crew lives in the Habitat.4. The crew leaves after about 500 days using the ascent vehicle, performs a rendezvous with the ERV in orbit around

Mars and returns to Earth.

1.3 AssumptionsThe mission concept is based upon those of Zubrin and the more conservative NASA Reference Mission (see referencearticles). However we are allowing for two major differences:

1. Assembly of the vehicle in LEO (i.e., at the ISS). The MMVS spacecraft is launched from the International SpaceStation (ISS), whose orbit is assumed to be circular. The Orbit of the Earth is assumed circular, and the orbits ofthe ISS, Earth, and Mars are co-planar.

2. The MMVS may perform a direct descent to Mars surface, or a transfer vehicle may be left in orbit around Mars forthe Earth return. The choice will be up to each design Team.

2.0 MMVS Operations ConceptThe MMVS must be designed for assembly in low Earth orbit at the International Space Station (ISS) using existingtechnology. The MMVS must safely carry a crew and necessary life support for a round trip from the ISS to Mars

2.1 Mission Profile:1. Launch MMVS components to the ISS using NTS Space Shuttle, and or expendable vehicles such as Russian

Energia.2. Assemble MMVS at the ISS using Canada’s SRMS (Shuttle Remote Manipulator System, SSRMS (Space Station

Remote Manipulator System), and SPDM (Special Purpose Dexterous Robot).3. Check out and Test MMVS at the ISS.4. MMVS unberths from ISS and departs for Mars when assured propellant stock has been manufactured by previous

Cargo landing.5. MMVS executes trajectory burns and maneuvers to enter Mars orbit or performs a direct descent.6. Landing on Mars at predetermined landing site which provides a propellant manufacturing facility with previously

manufactured propellant, and nuclear power plant (and Habitat an option).

– 2 –

Spacecraft Systems Design of a Manned Mars Vehicle System A Fourth Year Student Team Project Using the Internet

7. Explore Mars and obtain propellant from site storage8. Depart Mars9. Rendezvous if necessary with Earth return vehicle.

10. MMVS executes trajectory burns and maneuvers to rendezvous with the ISS.11. Berthing of MMVS to ISS

2.2 Additional MMVS Functions:Remote Control; Ground Operated (Option / Back-up)MMVS Command and Control

• Telefunction• Human-in-the-Loop• Automatic Control• Robotics• Cargo and propellant manipulation (loading / off-loading)• Vehicle berthing / deberthing

Transportation – Transport crew and/or cargo into space (sub-orbital or Earth orbit)Return of crew and cargoLife Support – Provide life support for IVA and EVA crew.

3.0 Team DesignsTable 3.1. Comparison of Some Student Team Designs against ISS

– 3 –


3.1 Team York http://www.yucc.yorku.ca/~ravi/mars/

– 4 –


3.2 Team Ryerson http://www.geocities.com/CapeCanaveral/Galaxy/7191/

– 5 –


3.3 Team Queen’s #1 http://lucy.me.queensu.ca/~usn99q1/

– 6 –


3.4 Team Queen’S #2 http://lucy.me.queensu.ca/~usn99q2/

– 7 –


3.5 Team Queen’s #4 http://lucy.me.queensu.ca/~usn99q4/

– 8 –


3.6 Team RMC http://www.rmc.ca/special/projects/mars

– 9 –


4.0 References1. Zubrin and the Mars Society: USA: http://www.marssociety.org2. Canada: http://canada.marssociety.org3. NASA: http://www.hq.nasa.gov/osf/hotlist/index.html4. http://members.aol.com/dsportree/exlinks.htm5. http://cmex-www.arc.nasa.gov 6. “Islands in the Sky” by S. Schmidt and R Zubrin, Wiley Popular7. Science, 1996, ISBN 0-471-13561-58. “The Case for Mars” by R. Zubrin with R. Wagner, Simon &9. Schuster, 1996, ISBN 0-684-82757-3

10. “The Future of Space Exploration,” Scientific American (May 1999) which contains a few articles including Sending Humans to Mars byRobert Zubrin. http://www.sciam.com/specialissues/0399space/0399quicksummary.html

11. A magazine article: Popular Science, February 1999 “Manned Mission to Mars.”12. A magazine article: Newsweek, July 25, 1994 “Next Stop Mars.”

– 10 –


Subsurface Flow Wetlands for Wastewater Treatmentin Mars Prototype Testbeds and Mars Surface Habitats

Mark Nelson[1999]

AbstractWastewater treatment in space, as on Earth, is needed for elimination of health hazards but could also include recyclingand utilization of the valuable resources contained in sewage: nutrients and water. Prior to the Biosphere 2 experiment,1991-94, bioregenerative life support facilities, such as the Russian Bios-3, accomplished only re-use of urinewastewater. Biosphere 2, utilizing a surface-flow wetland treatment system, achieved total recycle of wastewater withinthe closed ecological system. The wetland system produced fodder for domestic animals and acceptable levels ofwastewater purification. Research and development subsequent to the Biosphere 2 experiment, in Mexico andIndonesia, have demonstrated the advantages of subsurface flow wetlands. These advantages include: increasedtreatment per unit area, lower maintenance and operating time requirements, safer production of food crops, capabilityof sustaining high biodiversity and elimination of odor and accidental contact. This type of ecological engineering candemonstrate the congruence of solving environmental problems on Earth and advancing space exploration andhabitation. “Wastewater gardens” can be modified for space habitats to lower space and mass requirements, and can bea valuable part of overall food production, as well as assisting in air and water purification.

Wastewater Health and Environmental Problems – On EarthPollution of water resources by improperly or inadequately treated domestic wastewater (sewage) contaminates drinkingwater supplies and so is a leading cause of human disease worldwide (U.N., 1995). Health problems related to sewageare widespread, ranging from children swimming in open sewage treatment ponds, failure of leachfields due to wetseason inundation, and sewage effluent pollution of groundwater, rivers and lakes with adverse impact on drinking waterquality and recreational use of these resources. Water pollution includes pathogens carried by improperly treatedsewage and potentially toxic chemicals. Pathogens include disease-causing bacteria, protozoa, viruses and helminths.Chemical hazards include heavy metals, organic chemicals, and nitrates in sufficient concentrations to cause illness(Krishnan and Smith, 1987).

Especially for small, rural and isolated communities, there is great expense and difficulty in maintaining the highlytechnical systems that they are given. It is frequently reported that such systems are poorly maintained, theirperformance declines with age, and inadequate sewage treatment results. For developing countries, there is greatdifficulty in the high costs of sewage collection and the centralized conventional (high tech) sewage treatment facilityitself (Reed et al, 1995).

In addition to issues of human health, the release of nutrients from wastewater causes eutrophication (nutrient pollution)in the environment, leading to a wide range of environmental problems. These negative impacts from wastewaterdischarge include coral reef decline, ecological degradation of rivers and lakes including oxygen depletion/fish kill, andgiving competitive advantage to weed species over native plants in ecosystems impacted by release of humanwastewater.

New Ecological ApproachesBut the past several decades has also produced development of new approaches to wastewater utilization, stemmingfrom a fundamental change of perspective based on a total ecosystem approach. “Wastewater” is in fact a valuablesource of nutrients and water, upon which ecologically flourishing wetlands can exist. Wetland scientists havedemonstrated that not only natural but also properly designed and constructed man-made wetland ecosystems areextremely efficient at utilizing and cleaning such nutrient-rich waters (Mitsch and Gosselink, 1993,).

– 1 –

Mark Nelson; Chairman, Institute of Ecotechnics, Vice President, Wetland Treatment Systems, Biosphere Foundation; 7 Silver Hills Rd.,Santa Fe, NM 87505, Tel. 505 474 0209; Fax 505 424 3336; E-mail: [email protected]

The new disciplines of “ecological engineering” and ecotechnics seek to utilize predominately natural, ecologicalmechanisms in integrating human economy with the biospheric ecology. This approach turns out not only to be easy tomaintain but highly efficient in turning what was previously “waste” into green plants and reusable water. Wetlands arealso lower cost, in that there is far less reliance on complex technology, which is capital and maintenance-intensive, anduses much electricity / fuel. Designing the wetlands to do on-site treatment greatly reduces the costs of sewage collection.The use of ecologically constructed wetlands for human sewage treatment relies on the ability of green plants and non-pathogenic microbes rather than expensive machinery. Designed wetlands create a “buffer” ecosystem between the humaneconomy and the environment to mitigate negative impacts, increasingly illegal as well as unpleasant and unhealthy.

Wastewater Treatment in Closed Ecological Life Support SystemsPrior to the Biosphere 2 experiment (1991-1994), the most advanced testbed for bioregenerative, closed ecologicalsystem space research was the Bios-3 facility operated by the Institute of Biophysics, Siberia. The 3-6 month long 2-person closure experiments in Bios-3 achieved near total air and water purification, some 50% of food production, butonly recycled the crew’s urine. Solid metabolic wastes were exported from the facility (Terskov et al, 1979).

NASA scientists, led by Bill Wolverton, at Stennis Space Center experimented with wetland systems and applied themto NASA testbeds in the 1980s, but not in the context of human closure and life support experiments (Wolverton, 1990).The wetland treatment approach was further developed by the creators of Biosphere 2, and tested in a very small systemfor one-person closure experiments of 1-21 days in the Biosphere 2 Test Module before application for the design crewsize of 8-10 people in Biosphere 2 (Alling et al, 1990, Nelson et al, 1994).

In Biosphere 2, the wastewater system functioned as part of the sustainable food production system through theproduction of forage for domestic animals, and by the utilization of excess nutrients remaining in the wastewater effluentfor crop irrigation (Nelson, in press). The system handled all wastewater from the human habitat (toilet, kitchen,shower, laundry), domestic animal urine + pen washdown water, and effluent from medical/analytical laboratories andworkshops inside the facility. The system used anaerobic holding tanks (which functioned in a similar fashion to septictanks) as a first step, then circulated the wastewater between three interconnected fiberglass tanks which contained thewetland system. The system contained soil-rooted emergent wetland vegetation and floating aquatic plants in the waterchannels. Wastewater input averaged around 260 gallons/day (1 m3/day) into a total wetland area of 41 m2 andproduced 1,213 kg of vegetation during the 2-year experiment that was periodically cut for fodder to feed domesticanimals. Available sunlight was a limiting factor for plant growth, as only 40-50% of outside sunlight was receivedinside Biosphere 2. Biochemical oxygen demand (BOD), a measure of total organics in the water, was reduced by 75%from influent levels from the holding tanks. Final disinfection (if needed) was with high intensity UV lights (Nelson etal, 1998b). Since the health status of the crew was known, and no infectious diseases were present, the disinfection wasnot used during the two-year closure.

The 2-year closure of Biosphere 2 (1991-3) marked the first time that all wastewater was successfully recycled withina closed ecological life support system for people. The wetland treatment system continued to be used during the sevenmonth second closure experiment with a 7-person crew (March-September 1994). The system included 15 species ofvascular wetland plants, and provided additional wildlife habitat (Nelson, 1998b).

Research and Development with Wastewater Gardens (Approach)In research subsequent to the Biosphere 2 experiment, the author working in collaboration with the Planetary Coral ReefFoundation (a division of Biospheres Foundation) and the eminent systems ecologist, Prof. H. T. Odum of the Centerfor Wetlands at the University of Florida, developed an innovative approach to wastewater treatment using man-madewetlands, employing subsurface flow (Nelson, 1998a). This basic approach, which the Institute of Ecotechnics hasrefined, has been extensively tested and successfully applied in the United States and Europe over the past severaldecades (EPA, 1993). The Institute’s advanced design, Wastewater Gardens, which raises artificial wetlands to acomplete system, is now operating in over forty sites in southern Mexico, Belize and in Bali, Indonesia.

– 2 –

Subsurface Flow Wetlands for Wastewater Treatment in Mars Prototype Testbeds and Mars Surface Habitats

The Ecotechnics’ system uses simple but very effective design principles. Primary treatment, to separate solids, occursin a conventional, watertight septic tank or settling lagoon. But then instead of passing directly into a leachfield, withits attendant problems of little further treatment, smell, clogging and large size, the nutrient-rich wastewater effluent isfed into a lined, two-cell, subsurface flow wetland. In this type of wetland the sewage water is kept 5-10 cm. belowthe surface of a bed (0.5 – 1 m deep) of gravel. The treatment compartments are planted with a wide variety of wetlandplants, specially selected for the locality, into the gravel bed filled with sewage water. As entering effluent overflowsthe first stage cell, it passes to the second, and then to a comparatively small subsurface discharge or the treated watercan be recycled for further irrigation of lawns, shrubs, flowers or trees. Wastewater is generally held in the wetlandsystems for 5-7 days.

Subsurface flow systems have long hydraulic residence times and through a variety of mechanisms (Table 1) haveachieved large reductions in coliform bacteria without the use of disinfectants like chlorine used in conventional sewagetreatment (Reed et al., 1995). Chlorine has the potential to form toxic byproducts, such as chloramine, when releasedinto marine environments (Berg, 1975). Bacteria can break down chlorinated hydrocarbons into compounds that maybe far more dangerous than the original ones (Gunnerson, 1988), and sometimes de-chlorination has been required byregulatory agencies, further adding to the expense of such approaches (Kott, 1975). Subsurface wetlands use little orno electricity and technology and require little technical supervision once installed (Cooper, 1992, Steiner and Freeman,1989; Green and Upton, 1992; Steiner et al, 1992).

Table 1. Contaminant removal mechanisms in subsurface flow wetlands (after Watson et al., 1989)

Wastewater Garden – System AdvantagesAdvantages of the ecological subsurface flow wetland approach include:

1. Fecal coliform bacteria are reduced more than 99% in the wetlands, without the use of expensive, environmentallyharmful chemicals like chlorine. Biochemical oxygen demand (BOD) reduced 85-90% from influent levels, andremoval of nitrogen and phosphorus is substantial.

– 3 –


2. The wetlands are low-cost, low-tech and long-lived. Maintenance requirements are simple. These systems requireonly 5-10% of the labor and expense of more technical wastewater treatment systems.

3. There is no malodor as the sewage is kept from contact with the air.4. There are no mosquito-breeding or other nuisances associated with open wastewater (e.g., sewage lagoons or

surface-flow wetlands).5. The possibility of accidental public contact with the sewage is virtually eliminated as the sewage is kept below the

surface of the gravel bed.6. Subsurface flow wetland systems are capable of extremely high rates of wastewater cleaning. In research over the

past several decades, this type of wetland, even in its earlier design forms, has a well-documented track record ofconsistently cleaning water to levels better than municipal standards for wastewater treatment.

7. The intensity of treatment is such that only 1/2 - 1/5 the area is required compared to a surface-flow wetland (Kadlec andKnight, 1996). Every particle of gravel becomes colonized by the natural variety of microbes that are effective in utilizingand treating wastewater, and the root systems and water/nutrient uptake of the plants increase treatment efficiency.

8. Where higher treatment than normal municipal standards is required for special purposes, an increase in wetlandarea can provide the equivalent of advanced water treatment.

9. Significantly less wastewater (35-70% depending on design) is discharged from these special wetlands, because theplants use large quantities of water in their transpiration.

10. Subsurface wetlands can be exactly sized from small units for a single residence to larger areas for small city/townsystems. On the other hand, new demands can easily be met by simple unit expansion.

11. The wetland systems add considerably to the landscape beauty in communities where they are used, and can alsoinclude plants to be harvested for useful or salable products.

In detailed research conducted along the coast of the Yucatan, in southeastern Mexico, and critically checked byUniversity of Florida scientists, Wastewater Gardens™ were tested as a means of preventing pollution damage to off-shore coral reefs. An area of 3-4 square meters of wetland per full-time resident proved capable of removing 85-90%of BOD, nitrogen and phosphorus, and fecal coliform bacteria was reduced 99.8+% without use of chemicals. TwoWastewater Gardens totaling 130 square meters, served to treat the gray and black water of 40 residents, and supported65-70 varieties of wetland plants. Biodiversity was three times greater than in adjoining natural mangrove wetlands,and only 5% less than in the inland tropical forest areas (Nelson, 1998a).

Table 2 compares the prototype Wastewater Gardens researched in the Yucatan, Mexico with average values forsubsurface and surface flow wetlands in North America (Kadlec and Knight, 1996, Nelson, 1998a). BOD loading forthe Yucatan wetlands is slightly higher than the average subsurface wetland and removal rates are higher (88% vs. 69%).Total phosphorus loading in the Yucatan was less than 40% that of average North American systems and removal is 76%vs. 32%. Nitrogen loading in the Yucatan is around 4/5 that of typical subsurface flow wetlands, and removal efficiencyis 79% vs. 56% for North American systems. Many subsurface flow wetlands in temperate climates are started withjust a few plant species, often virtually monocultural systems. These systems composed exclusively of Typha latifolia,Scirpus spp. or Phragmites australis are less attractive and less beneficial for wildlife. However, some large surfaceflow systems have included natural wetlands and been managed to foster a wider biodiversity of plants and habitats(Kadlec and Knight, 1997; Reed et al, 1995).

The plants, specially selected for ecosystem fit and productivity, used in the Wastewater Garden systems are key to theirperformance. In addition to direct uptake of the nutrients contained in the sewage water, wetland plants act like oxygen-pumps, supplying their root systems with the aeration required for growth. In the process, the plants create micro-zonesfor aerobic bacteria to flourish. Thus, the wetland has both anaerobic and aerobic biochemical reactions, which aids inrecycling of nutrients and treatment of the wastewater.

The opportunities for beneficial and productive use of the wetland plants give a great range of choice. The wetlandscan be used for creating beautiful gardens and landscape diversity of home, business, hotel or town. The gardens canalso feature productive plants, such as flowers for sale, fiber / fodder plants and timber trees. Plants harvested above

– 4 –


the dry surface of the gravel pose no danger of wastewater contamination, and so food crops can be grown. Otheropportunities include botanic garden displays, and for creating additional areas of wetland ecosystems, with richbiodiversity, wildlife and bird habitat, to compensate for wetland loss elsewhere.

Table 2. Comparison of loading rates and removal efficiency of Yucatan, Mexico Wastewater Gardens(with average North American surface and subsurface flow wetlands)

(Nelson, 1998a, Kadlec and Knight, 1996)

Space Applications of the TechnologyThis approach to wastewater seems ideal to support long-term space exploration and habitation where bioregenerativeresupply of food is utilized. This is because the wetland treatment system requires the same environmental conditionsnecessary for crop plant growth: light (sunlight or artificially produced) and warm temperatures. Since the wetlandsystems rely on green plants and microbes, they perform even better in warm, sunny conditions than the successfulwetland systems in cold climates such as Canada, Germany, the United Kingdom, and northern United States. In milderconditions with higher temperatures and increased light, system effectiveness is high year-round. These environmentalconditions may well be the case in “space greenhouses” as such conditions optimize crop growth and thus will alsominimize greenhouse area requirements.

The low-labor requirements and absence of consumables also makes subsurface flow wetlands advantageous for spaceapplication. Once set-up, they will require no resupply from Earth of machinery or chemicals and will make littledemand on valuable astronaut time.

It is probable from what we currently know of Mars surface geology that Martian soil and rocks can be mined andscreened to supply the gravel substrate of the wetland systems. Mars soil evidently contains many of the micro-nutrientsnecessary for life, and what is lacking may be amended by the nutrients contained in human wastewater (Stoker et al,1993, McKay et al, 1993). For initial wetland systems, one strategy to lower mass requirements is by using lightweightplastic (e.g., Styrofoam) which would provide the required microbial surface area, but without the weight ofconventional rock gravels.

– 5 –


A further consideration favoring bioregenerative approaches to wastewater treatment for space habitats is that many ofthe more technical approaches previously advocated, such as wet oxidation and supercritical oxidation, in addition torequiring more technical maintenance, labor and power, result in the reduction of the wastewater nutrients to simplemolecular form, with a consequent loss of chemical bond energy (Swartzkopf and Cullingford, 1990). This is not trueof wetland systems that recycle the valuable nutrients in forms available for bacteria, algae and higher plants.

The required wetland treatment area for Mars habitats can be considerably smaller than in most terrestrial applications,if the wetland is connected to the main food-cropping agricultural system. In this case, the holding tanks and smallwetland area can serve to separate solids, and initiate microbial purification of the wastewater. There would be no needfor achieving high nutrient uptake, as the effluent water from the wetlands would carry those nutrients to the soils of theagriculture system, helping to maintain soil fertility. The plants grown in the wetlands (e.g., rice, banana etc.) wouldadd to overall food production. There are also synergetic benefits of the use of this wetland treatment system for airpurification and potable water production. The wetlands will help recycle and purify the internal air of the space habitat.The high transpiration rates of wetland plants release pure water to the internal habitat atmosphere that can be condensedas a source of potable water (as was successfully done in Biosphere 2).

For use in prototype Mars bases (such as the Arctic base currently envisaged by the Mars Society for Devon Island inthe Canadian Arctic), the wetland systems may assist in prevention of contamination of local surface and groundwaterresources. Subsurface flow wetlands may be located inside the prototype Mars habitat, since they have no malodor andwould give the crew the pleasure of beautiful gardens. Artificial lights would be needed for wetland plant growth buttheir waste heat might effectively warm the interior. Wetland plants would help prevent “sick building syndrome” byabsorbing trace gases that accumulate in tightly sealed buildings. In addition, developing wetland systems for use in theoutside Arctic environment could be useful in preventing water pollution from the other members of the scientificresearch teams. Such specially developed wetland systems, using plants native to the region, might elicit interest foruse in indigenous communities, National Park facilities and mining towns in the north of Canada.

References1. Alling, A., Leigh, L., MacCallum, T. and N. Alvarez, 1990. Biosphere 2 Test Module Experimentation Program, pp. 23-32 in: Biological Life

Support Technologies: Commercial Opportunities, M. Nelson and G. Soffen (eds.), NASA Conference Publication 3094, Washington D.C.2. Berg, G., 1975. Regional problems with sea outfall of sewage on the coasts of the United States, pp. 17-22, In: Discharge of Sewage from Sea

Outfalls, A.L. Gameson (ed.), Pergamon Press, Oxford.3. Cooper, P.F., 1992. The Use of Reed Bed Systems to Treat Domestic Sewage: The Present Situation in the United Kingdom, pp. 153-172, in

Constructed Wetlands for Water Quality Improvement, Moshiri, G.A. (ed.), Lewis Publishers, Boca Raton, FL.4. EPA (Environmental Protection Agency), 1993b. Subsurface Flow Constructed Wetlands for Wastewater Treatment: A Technology

Assessment, U.S. EPA Office of Water (4204), EPA 832-R-93-008, Washington, D.C.5. Green, M.B. and J. Upton, 1992. Reed bed treatment for small communities: U.K. experience, pp. 518-524 in Constructed Wetlands for Water

Quality Improvement, Moshiri, G.A. (ed.), Lewis Publishers, Boca Raton, FL.6. Gunnerson, C.G., 1988. Wastewater management for coastal cities: the ocean disposal option, World Bank Technical Paper Nbr. 77, World

Bank, Washington, D.C.7. Kadlec, R.H. and R.L. Knight, 1996. Treatment Wetlands, Lewis Publishers, Boca Raton, FL.8. Kott, Y., 1975. Effluent quality of chlorinated sewage discharged from sea outfalls, pp. 155-164, In: Discharge of Sewage from Sea Outfalls,

A.L. Gameson (ed.), Pergamon Press, Oxford.9. Krishnan, S.B. and J.E. Smith, 1987. Public Health Issues of Aquatic Systems Used for Wastewater Treatment, pp. 855-878, in: Aquatic Plants

for Water Treatment and Resource Recovery, K.R. Reddy and W.H. Smith (eds.), Magnolia Publ., Orlando, FL.10. McKay, C.P., Meyer, T.R., Boston, P.J., Nelson, M., MacCallum, T., and O. Gwynne, 1993. Utilizing Martian resources for life support, pp.

819-844, in: Resources of Near-Earth Space, eds. J.S. Lewis, M.S. Matthews and M.L. Guerrieri, University of Arizona Press, Tucson.11. Mitsch, W.J. and J.G. Gosselink, 1993. Wetlands, 2nd Ed., Van Nostrand Rheinhold, NY.12. Nelson, M., 1998a. Limestone Wetland Mesocosm for Recycling Saline Wastewater in Coastal Yucatan, Mexico. Ph.D. Dissertation, Dept. of

Environmental Engineering Sciences, University of Florida, Gainesville.13. Nelson, M., 1998b. Wetland systems for bioregenerative reclamation of wastewater – from closed systems to developed countries, Journal of

Life Support and Biosphere Science, vol. 5:357-369.14. Nelson, M., Finn, M, Wilson, C., Zabel, B., van Thillo, M., Hawes, P., and R. Fernandez, (in press). Bioregenerative recycle of wastewater in

Biosphere 2 using a created wetland: two year results, Ecological Engineering, issue on Biosphere 2.15. Nelson, M., Dempster, W., Alvarez-Romo, N. and T. MacCallum, 1994. Atmospheric dynamics and bioregenerative technologies in a soil-

based ecological life support system: initial results from Biosphere 2, Adv. Space Res. 14 (11): 417-426.

– 6 –


16. Reed, S.C., Crites, R.W., and E.J. Middlebrooks, 1995. Natural Systems for Waste Management and Treatment, McGraw-Hill, NY.17. Steiner, G.R. and R.J. Freeman, 1989. Configuration and substrate design considerations for constructed wetlands wastewater treatment, pp.

363-377 in Constructed wetlands for Wastewater Treatment: Municipal, Industrial and Agricultural, Hammer, D.A. (Ed.), Lewis Publishers,Boca Raton, FL.

18. Steiner, G.R., Watson, J.T. and K.D. Choate, 1992. General design, construction and operation guidelines for small constructed wetlandswastewater treatment systems, pp. 499-507, in Constructed Wetlands for Water Quality Improvement, Moshiri, G.A. (ed.), Lewis Publishers,Boca Raton, FL.

19. Stoker, C.R., Gooding, J.L., Roush, T., Banin, A., Burt, D., Clark, B.C., Flynn, G. and O. Gwynne, 1993.The physical and chemical propertiesand resource potential of Martian surface soils, in: Resources of Near-Earth Space, eds. J.S. Lewis, M.S. Matthews and M.L. Guerrieri,University of Arizona Press, Tucson.

20. Swartzkopf. S. and H. Cullingford, 1990. Conceptual design for a lunar base CELSS, in: Engineering, Construction and Operations in SpaceII, ed. S. Johnson and J. Wetzel, American Society of Civil Engineers.

21. Terskov, I.A., Gitelson, J.I., Kovrov, B.G. et al. Closed System: Man-Higher Plants (Four-Month Experiment), translation of Nauka Press,Siberian Branch, Novocibirsk, 1979, NASA-TM-76452.

22. United Nations, 1995. Guidelines on Environmentally Sound Development of Coastal Tourism, Economic and Social Commission for Asiaand the Pacific.

23. Watson, J.T., Reed, S.C., Kadlec, R.H., Knight, R.L. and A.E. Whitehouse, 1989. Performance expectations and loading rates for constructedwetlands, pp. 319-348, in Constructed wetlands for Wastewater Treatment: Municipal, Industrial and Agricultural, Hammer, D.A. (Ed.), LewisPublishers, Boca Raton, FL.

24. Wolverton, B.C., 1990. Plants and their microbial assistants: nature’s answer to Earth’s environmental pollution problems, pp. 60-66, in:Biological Life Support Technologies: Commercial Opportunities, M. Nelson and G. Soffen (eds.), NASA Conference Publication 3094,Washington D.C.

– 7 –


2001mars society convention part 4

Documents

normobaric air

hypobaric air

inhalation of air

low o2 hypoxic environment

application of normobaric

hypoxia result

result of adaptation

hypoxic stimulation